Most indie developers use retro-themed art as a necessity, not as an aesthetic choice. Simpler art is less costly to produce, and less costly to animate. (animation is a HUGE time-sink) Small teams or individuals simply don't have the budget to produce Call-of-Duty levels of detailed graphics. Many of them are driven to such art styles out of desperation, as opposed to active choice.
Yea, and that's fair, but personally it destroys my interest in otherwise great games with interesting mechanics. If I had it my way I'd say 16 bit should be the minimum : Still easier to make but far more versatile and not limiting, especially for games using mechanics popularized in that era but drawn in 8 bit.... If you're making an 8 bit game then its weird to me having dash and other movements I've never used in an 8 bit game?
I sympathize for why to go 8 bit but at the same time I find them ugly and it's kept me away from at least a dozen or so games.