1. I don't personally mind some gear being locked to certain roles, because having a caster in heavy armor or a Dragoon set (which is stylistically specific to the job, more often than not) might seem a bit awkward, but I feel like some pieces could stand to be made into universal glamour pieces with different default color schemes or minor alterations ala the Anemos/Pagos gear or the Uraeus Coat.
I'd personally like to see more waist length jackets (the Anemos Jacket isn't bad but its length is very very strange.) Perhaps there could stand to be a bit more "casual formal" attire. The Scion Adventurer's Jacket was awesome, so maybe something akin to that only a bit simpler.
One thing that I could definitely get behind is making the race specific starter gear universal. I'd love to have my Hyur in something like the Miqo'te Vest, because I personally like that the most out of the starter gear.
2. I feel like it would be a lot of work the make such changes to the clothing color system (having dyeable "parts" rather than a preset dye pattern,) but it would be awesome if something like that could be implemented at some point. I think that part of it is that currently clothing on each character has to be loaded along with the dye choice, which is essentially loading two pieces of data. Adding in dyeable "parts" would mean that the game would have to load whatever clothing model is selected but also read each part for whatever color is being used. That probably wouldn't put too much of a strain on the system, but I could see altering what's in place already being a lot of work. I'd love something like that however!
Perhaps if something like that is added then maybe a tailor could be added to the major cities. You could visit them and alter your gear for a fee or provide dyes to do it for free. That way there would still be a market for dye on the boards.