Why aren't outfits modular?
Getting away from the original technical reason why they separated everything out into armours and outfits, at this point popularity will be the driving force. I know I;ve bought loads of them and some I find preferable to armours.
Whilst I understand the mix and match argument, being separate has a huge advantage of not requiring transmutation charges and can set a look over the top of armour whilst levelling – useful for alts and new players.
The reason simply seems to be, it is working for them and generating money.
Why aren’t Outfits modular? Because then they would be Armor Sets. The playerbase asked that Armor Sets not be sold so much in the Gem Store, so the Devs stated that Outfits would be sold, and Armor Sets would be earned in-game.
Sadly, it is not possible to please everyone when there are so many different preferences.
I just wish they would give the option to make the current armor headset visible instead of the outfit headset. I use shades on some of my characters and you can’t use them with outfits.