A lot of these forms seemed really unnecessary. I get for marketing purposes you couldn't keep Enchantix or Believix forever, but man, the conditions of obtaining some of these are really weird. Enchantix and Believix feel more like "final forms", meanwhile some of the later seasons have conditions like "a special bracelet" or were granted to the girls JUST BECAUSE they're the Winx Club?? Come on LOL
Granted, that's just because the writers were running out of ideas and the quality of the show really took a nose dive after S4 and the movie for S4.
They could have taken a lot more inspiration from Japanese Tokusatsu like Kamen Rider, though. Some of them have a lot of forms obtained through unique ways, then their final one is something that comes from within through a significant achievement.
I'm pretty sure some Magical Girl series have similar forms... I remember the girls in DoReMi got more forms as they grew stronger over time, not because of special items or artifacts
