This is a nice sentiment, but it's not necessarily true in a game where you have to work together with other players. Sometimes you play the job that your team needs you to play, even if you don't particularly like it. Everything has a cost.
It's hard to comment what this expansion's balance is like, in part because people are still gathering information about how the jobs play and can be optimized. Shadowbringers, in fairness, did have a fairly tight balance within roles. Heavensward and Stormblood most definitely did not. A lot of your post reads as someone naive to this game's earlier history. Double ranged is not a new phenomenon. It was actually the mandatory comp at one point, and you needed a DRG to make it work.
I think the reason why many tanks are currently downplaying damage output is because of two factors: first, because of how close the numbers were in Shadowbringers, and secondly, because of a declining contribution of tanks to overall raid damage. But it doesn't take much for this to start mattering again. PLD was probably overall the best defensive tank in Heavensward, especially where physical damage was concerned. DRK was often still a better choice even when it was at a significant defensive disadvantage. Why was that? I'll let you guess. Hint: It wasn't because of Living Dead. Why was WAR a mandatory pick in every comp in Heavensward? Again, I'll let you guess.
I agree that jobs should be designed first and foremost for fun. Both Heavensward DRK and the current iteration of RPR are fast paced with a strong focus on uptime and resource management. Jobs like these don't have to be the absolute best at everything for them to be fun. But you do still need to be in striking range of the best. It's incredibly frustrating to play a job that's really well designed yet no matter how mechanically polished your gameplay becomes, you're still not competitive. That's why damage balancing is so critical.
You do need to remember that you'll always see players from all jobs campaigning to see their chosen job buffed to unreasonable amounts of power. Oh, it's so unfair that my job, which is the only tank with two job-specific raidwide mitigation tools both of which work against all types of damage, has one which requires a heal proc. And we don't do the highest dps this expansion despite having a massive utility advantage over everyone else, that's unacceptable. With a dev team that's so focused on pleasing everyone and so afraid to show open disagreement, you always see the same jobs as the most common picks. And that's not because everything was perfectly designed for fun in ARR, it's because older jobs have more of a backing. But it creates a culture where you feel compelled to demand more unreasonable things to keep up.