I don't see them making subclasses a level 1 choiceMystic works if they lean into the half-caster angle, which is the approach I would take, in addition to removing Asian specific tropes (other cultures have magical warriors who eschew weapons). Making Subclass a Level 1 choice also would open up the design space to let different Subclasses be different. There are more Subclass possibilities for "Magical Martial Artist" than "Brawler" too. "Brawler" sounds redundant with a Fighter using an unarmed fighting style.
Their reasons for doing still apply, When you're making a character you're already making a choice in race, class, background, skills, equipment, and possibly spells or another class feature. That's a lot
Locking in your character to a subclass before you've even played them is a bit much