I came from competitive MOBA, FPS games like Counter Strike, League of Legends, etc, and there are certain champions/heroes I want to play more than others despite the skill gap difference between them. Say, in League of Legends, people love to play champions that are in favor of the meta, but I want to play champions like Yasuo, Zed, Riven, etc. Many people would say "why don't you go with the meta? It's more effective and some of them are even simpler than those you are playing right now." Indeed, but these champions are really fun when you start to understand the mechanic of those high skill cap champions and it felt more satisfying to use my brain to make creative gameplay instead of "right clicking to win" (Master Yi).

Same can be applied to FFXIV. I don't see many people running DRK while I run ID solo because I feel like they tend to favor effectiveness and low-effort gameplay to get pass the dungeons as fast as possible. I had played in a new preferred server in Japanese DB (Atomos), and out of 10 IDs I played in, 7-8 games I played with a DRK. The clear is significantly faster because everyone knows what to do: tanks don't do trash pull, or that's how I have seen so far - healer can DPS while still be able to heal tank at right times; everyone focuses at a single target. That's my experience so far, but what I want to say is, DRK isn't bad unless you want to speed run through IDs, and if you do, you should know what you are doing and you should bring a healer friend with you cause DRK doesn't have tanky stats but this class has a lot of sustain if you use your rotation right.