You're falling into the delusion that people don't follow cookie cutters when it comes to endgame. There will always, without fail, be a "best" way to spec your class/job/whatever when customization is a thing. The freedom of choice is non-existent when someone expects you (or the tool) to perform at the best it can be. When you look at a job such as BRD, they must be equipped with DEX, as that is their primary stat. If they expect the best output, they must gear towards that and whatever secondary is most beneficial to perform at their best or, in some cases, even decently.
Mathematics, when it comes to customization, will typically point out what is "best". There is no way around that. Likewise, even if another way to customize was considered "just as good", the players will not see it that way. There will always be a hands down perception about what should be done. Again, there is no way around that when it comes to output performance. Of course, just as it is now, someone could deviate from that and do whatever the hell they want. It definitely doesn't go over well with their peers though .
WoW's current spec/talent tree is a decent example of a game with "choice" in some areas. That choice however is in reference to rather useless abilities compared to the others. Those being things like vanity or QoL improvements outside of party situations. The other options are regarded as mandatory if you expect the (potentially) best output.
What you're asking for is a strict homogenization. There can be literally no difference between any ability (or job) in order for something to be 100% opinon based, outside of visual differences like animation. This is a game where people want to be different, but they also want to be treated equally. That difference comes at the cost of true freedom of choice however, in the name of balance. When people want to have options and know that there is a "best" route to take (e.g. DPS rotations or priorities), that choice already becomes hindered. We want complexity in our games, which is what such things do, since it means you can't just mash random buttons/keys and expect to be the best.
I get that part of what your goal is is the ability to customize to the point that you can have something like an accuracy build for one fight, then freely switch to straight damage output/mitigation/healing (depending on role) for another. That, however, is an argument that is not suited for cross-class discussion, since gear is your biggest modifier in games like this. That's an argument for stat changes/updates and such, which is something some of us have been wanting for a long while.
You are right, however, about the cross-class system being short sighted. Its limiting factors almost make it about as diverse of a selection as our bonus stat point distribution. It is, however, a system that will always have a best route to take. The opinions come in whether or not its important to be that way for said content, and that is entirely on the players, not the devs.