I believe, Honoka's gym outfit is also meant as a substitute for a missing fan design costume. It doesn't really fit the rest of Honoka's wardrobe, is also a copy paste of old fetish DLC and didn't all new characters get only two different default costumes and color variations of it?
I'm not so sure on Honoka's gym outfit being a substitute, after all she is a schoolgirl and is Japanese: she would have definitely got that outfit sooner or later (together with the cheerleader one), but such gym uniforms are so popular and considered a sexy outfit in Japan that TN thought to make a favor to the interested fans including it for free in the disc. Also, I believe that for the characteristics overmentioned Honoka is pretty fitting for a similar outfits, definitely more than Christie, Rachel or Lisa XD
[Also, personally I think that the maid outfit is a funny outfit prettying fitting Nyotengu for some reasons, a shame that can't be really appreciated considering that is far from being an unique outfit in the vestiary of the game...]
Only Marie Rose got 2 outfits in 2 color variations at her debut (that appears pretty strange considering her popularity, very likely this was given from different priorities of the developers at the time) and Raidou (but being a male and a boss fighter, make sense to get a such portrayal to his debut). At their debut Phase 4 got 3 outfits in 2 different colors (6 costumes), Nyotengu got 3 outfits in 3 different colors (9 costumes) and Honoka got
5 6 outfits, 5 original ones (her C2 actually being a variation of her C1) and one common outfit (the gym one).