Comment by SyzygyRhythm

Graphics is part of the problem, certainly, but at least it's moderately independent of the rest. You can scale the quality up and down without affecting the rest (within limits: having many armor variants, etc. are more costly with greater graphic fidelity). As far as the rest: all of these different gameplay mechanics have a complexity cost. You can try to add everything, but then you run into balance problems and/or it just feels too complex for most people, not to mention having a high development cost. So something needs to be simplified, and that means either reducing the depth or reducing the mechanics. But if you've already decided to include something for everyone, that necessarily means that everything is shallow.