Only because Precure is doing fine with changing cast each year doesnt mean it would work for Sailor Moon.
Actually it's not working just for Precure, it's work also for kamen rider, Power ranger and Digimon. 3 series made by Toei, it work also for Sunrise with Gundam who is the most successful series in japan, same for the long running manga Jojo Bizarre adventure.
(And I want to point that the great JRPG series also change the cast after each game because after 60 hours there is nothing more to add about the cast)
Every title need a change of cast after 150 episodes of a show, change the lore is not needed(and would be a bad idea), but the cast...
There is nothing more to said about the original sailorsenshi, even the last season of the original show were more about the antagonist than the main characters
But we meet here a major problem in every franchise (and the reason behind the stagnation of maany franchise) There "what a Show need to evolve and to be interesting, and what the fan wants"
The gold saint in Saint seiya are not need, they even are the Poison of the series, but the fan want it, they don't buy the serie without the Gold. It's why saint seiya is Doomed.
The main problem of Dragonball Super came from they fact the serie focus too much on Goku and Vegeta and even make return old character like C17, Future Trunks and Freezer. It's odd when DBZ tried to make Gohan, Trunks and Goten take the main role in Boo saga. But as Goku, Vegeta and Freezer are more popular than Gohan, Goten and kid Trunks, the show focus on them even if it make the serie less good
And it's similar for sailormoon, the original cast is not needed, they are character overused, they already received more than 150 episode and except by changing their role, their is nothing new to tell about them. But the fan can't see a serie without them.
they would have never wanted to create of it something that would rival PreCure. PreCure is their own cow they can milk endlessly, while Sailor Moon is a cow they share and can milk for no more than 5 seasons.
actually, I read Toei financial report each years in 2014 and 2015, Precure series made the worst sales of the licence, Toei animation made as more money from sailormoon than Precure. Toei was unable to export Pretty Cure out of japan.Pretty Cure is slowly dying since Heartcatch have been concluded (the sale and TV rating are lower each years).
Precure regain the third place in Toei animation report in 2016 in 2017 only because of Glitter Force but in Japan, the problem is still the same, Pretty cure populary continue to fall.
It's the reason Toei wanted Sailormoon to take the place of Precure. By doing a Reboot there was no obligation to limit the serie to 5 season.
And Pretty Cure, even with it's own popularity is still only the third magical girl show in term of money earned. Sailor Moon and Winx are the 2 firsts(and actually it's nearly impossible to said which one is first between the 2)
Naoko on the other hand might have wanted another studio to work with,
Actually, she can't. while Sailor V is her manga, Sailormoon was co created by Toei animation. Sailormoon is a project similar to Dragonball Super, nor the manga and the anime are the original, the two are the original. Toei can't do a sailormoon serie, but Naoko can't do a anime version of sailormoon without Toei animation
but Sailor Moon is old revival with mostly adult fanbase, so a PreCure similar handling wouldn't have worked. Kids would have loved it, but they have never been the main Crystal target anyway.
Toei wanted the kid to be the Target of the show, they wanted to expand the fanbase.
Toei animation always said it, they are doing show for kids and are not interested about doing show for adult except if some director want to create some original (like Pop in Q, Kado, Kyosogiga and Mononoke).
The reason Pretty Cure failed to find it way in west for long time is because Toei refused distributor who would have aimed the serie for adult in west, they prefrre that Saban make their own serie with Pretty cure than exporting the serie for adult.
They also refused Dragonball Super to be simulcasted in west and said "Dragonball Super will be only showed in West on TV with a dub because simulcast and Sub are not made for kids"
Toei wanted the revival of sailormoon to be aimed for kids, like the original was.
And I don't understand why an anniversary project would have been aimed for original public.
Are you aware than Saint seiya Omega was the 25 years anniversary project for Saint seiya and Toei made what they planned to do with their Precured Sailormoon(But Kurumada is not like Naoko, he know saint seiya didn't age well and wanted to give to the kid their Saint seiya, so he said ok, like he say ok to every project who expand the serie).
And the 60 years anniversary project of Toei animation was not a serie who made the studio popular, it was Pop In Q, a show who have nothing to do with Toei works.
And the 40 years anniversary project of Tatsunoko biggest licence serie Gatchaman was Gatchaman crowds, a Show who have nearly nothing with the original serie (and was handled by a Toei animation director)
the show was hated by the fan of Gatchaman but was loved by the new public and it was what the serie needed because Gatchaman is an old serie and have no place in 2010's
I thinks it the same for Sailormoon the title who is too much marked as a 90's series, the character are cliché, the charadesign seem dated, the mood seem dated(long skirt middle school uniform and arcade gamer in 2014 is just silly)
The character, story and design need to be changed to fit better to 2014 public. The concept of Crystal is a bad idea because of that, between 2000 and 2003 for the 10 years of sailormmon, it would have been a good idea, but 10 years later no...
and TOEI have never been a studio that could produce something nice with the slightest budget cuts.
Actually it not fully correct, Saint seiya Omega season 1 planning was an hell(Morio Hatano and Umakoshi took vacation just after it) and everything was rushed and there was many budget limitation.
But the serie is good and even better than the original in some aspect because it's made by people who have a nearly complete freedom to do what they wanted and love their work. Umakoshi started to work on animation because of saint seiya movie and he said Saint seiya Omega was the serie where he had the biggest amount of liberty to create his design because there was no original work to follow and no need to create design to make goodies and Hatano said the staff made the storie they wanted even when they took the risk to provoke censorship.
Actually Toei animation don't do good works when they make a serie they don't want to do just because of a contract or if someone force them to follow a bad story(it's pretty clear Dragonball Super problem came also from the fact Toriyama produce an uninteresting storyline and Toei is not motivated to animated it, by exemple)
Sailormoon Crystal is not the Sailormoon they wanted so the just just don't try, they doing this because they are forced by contract but make no effort to make it good