Honestly, this whole "X is more important than Y element for a good rpg" mindset feels more like an excuse for laziness in my opinion.
Obviously, Everything has equal importance if you're trying to reach out to most people out there,
Yes it's pretty difficult to pull correctly and time consuming, and that's the reason games are made with development teams, however, and in my opinion, at least outside the professional game making scene, A designer doesn't have to excel at everything, but otherwise, should be at an acceptable level at everything and perhaps really stand out in one particular area.
To further explain this, If you're making a game based on your own preferences and strengths, then you will most likely cater to one specific group of people, i.e if your game revolves around engaging gameplay, your game will receive the most attention from those who value good gameplay and mechanics...however I do not think this is an excuse to completely neglect other areas such as art and music, it is not really "Focusing in one aspect because that's what I like the most" That's just being lazy.
Same goes for graphically inclined people, your game featuring amazing presentation and maps won't justify bad/generic gameplay.
Same goes for music,writing,and so on.
so TL;DR
It's okay to be good in one particular area and focus on that, it isn't okay to neglect everything else because of that.
Regardless of preferences, talents and biases, a game should be at an acceptable level in all areas and perhaps stand out in a particular one.