Matching Set Bonus's

[Duelle]

I'd much rather have set bonuses where it isn't straight up you have to wear these 5 pieces for the effect and more open ended with a large variety of gear and the bonus are available through wearing any variety.

Depends on how the bonuses can be used. If it's a beneficial change to class mechanics, then the devs are justified in making you wear the 5-piece set to get that. Not that anyone has ever forced players to wear more than 4 pieces at that (even WoW has up to 4-piece set bonuses for their class-specific tier gear).

I don't really understand why there's an issue with people being mismatched, if that's how they choose to maximize their abilities then let it be.

In the case of the OP, it's not because other players look like mismatched clowns. It's because to perform on a similar level to those people, she/he would have to look like a mismatched clown as well. Some players, myself included, are very affected by aesthetics.

To setup a method in which set bonuses would be the top choice when it comes to gear would completely defeat the purpose of gearing up to your design and focusing on just wearing a set to get the best stats possible.

Appearance tabs/transmogrification/vanity slots. Pick your poison.

There are right ways to go about like the GC set bonuses but having it to specified just leaves it open to making gear selection very restrictive in the long haul.

While giving the developers leeway in terms of gear design because they know they can put the really good bonuses on the AF/tier gear for that specific set of content.

Which gives a two-fold bonus. One being that they can design progression as a build up to the gear with set bonuses (AF/Tier). Two being that they have an easier time designing and balancing battle content when said gear with bonuses, being the apex (or close enough for balance purposes) for that content set, will be the measuring stick for class/job performance. There are benefits to that type of design.