Sorry but now you are trying to invalidate a perfectly good way to play D&D.
Why?
Because it is fun.
No further justification is needed. Stop trying to tell others how to have fun, okay?
Sorry if I sound antagonistic, but I'm trying to illustrate why this "because it is fun" approach leads to confusion.
It's almost a non-statement. "Why do you guys wrap your PHBs in orange peels and drop them off the parking garage?" "Because it is fun!"
You can't move logically from "I do X because it is fun" to "Therefore, the game should support Y because it makes X more fun." There's an intermediate step of explaining how Y makes X more fun.
If what you really enjoy is raiding dungeons, then raid dungeons.
If what you really enjoy is shopping for magic items, well, that's not the same as raiding dungeons, that's a shopping mini-game. People say "If I wanted to be a noble/merchant/guildmaster/etc. I'd have stayed in town." Well I counter with, "If you want to go shopping, play a shopping mini-game."
Can D&D be all things to all people? They have to draw the line somewhere. I think domain-management rules would be sweet, but when I see modules for data-mining or project-management or animal-husbandry -- yeah I'll skip those. I'm OK with skipping the shopping mini-game too.
If D&D can't be all things to all people, I think it should be a role-playing game first. I've no doubt the shopping mini-game can be tacked on later for people who want it.