The Queen is back. Anyway.
Let me just preface everything by saying - no, the characters don't spend the vast majority of the time in the 2011 anime transformed. Madoka herself does not even become a Magical Girl until the last episode (though her form is shown beforehand). While them being Magical Girls is obviously important to the plot, they typically only transform for action scenes, more-or-less.
Additionally, even in the 2011 anime, the characters don't *only* have either the school uniform or the MG one. Kyoko never wears the Mitakihara school uniform in the 2011 anime. Madoka and Sayaka (maybe others too, can't remember) have PE gym clothes, Homura and Madoka have pajamas. Madoka *literally turns into a god* in the last episode. Yes, the two options are their most common, and for a reason, but even then they're not exclusive. Not to mention all the promo material or even fan-outfits.
Also. Can we please, for love's sake, stop acting like the 2011 anime is the only installment of Madoka Magica ever made? PMMM has three (upcoming four, plus a short-feature) movies, seven video games, one of them adapted into an anime, 2 mangas and stage play of its own; and a manga magazine *just for PMMM stories* that ran for 30 volumes, containing both stories featuring the quintet from the 2011 anime *and* original ones with brand-new casts, not to mention one-off collabs with all kinds of brands. Even just the main quintet/sextet has *way* more costumes than just MG/civilian.
Quoting what I said in topic #23010:
For some stats - this search: tamaki_iroha solo has 54% of posts also tagged as Magical Girl. And I keep that tag in good shape for Magia Record (if you can excuse canon-tagging for characters like Izumi Kanagi or Kureha Yuna).
Obviously that statistic didn't take into account stuff like "untransformed Iroha standing next to transformed anyone else", but still, it paints an approximate picture. For another character, Miwa Mitsune, 67/209 (32%) feature her MG form. I expect similar statistics for bigger tags like Madoka too. I think 30~50% is already enough to justify chartags like that. Especially since the quintet won't be the only characters benefitting from that change; all the MagiReco originals will likely end up with the same treatment, and *those* have many designs by, well, design.
Plus, let's not forget - today's status quo is not tomorrow's status quo. While I never expect PMMM to have quite the upload explosion it had in 2011 on Danbooru ever again, let me just remind you that the upcoming movie Mahou Shoujo Madoka Magica: Walpurgis no Kaiten features tons of brand-new costumes - a new school uniform that looks kinda like the Mitakihara one (post #6851079), and new magical girl outfits, see post #6673371 (Mami) post #7071875 (Madoka, Homura), post #7553429 (Kyoko, Sayaka). Maybe in 10 years that'll be what they'll be wearing by default in new installments. Who am I to say?
Additionally, I think comparing Magical Girl form/other forms tagging to gacha tagging is not the best comparison. If anything, I believe it'd be closer to vTubers - multiple "default" costumes to be swapped to and from freely (like the costumes they stream in), plus some extra chartags for more one-off costumes (collabs and such... but also gacha tagging, admittedly).