I can concur with some of what Memo said. Many veterans that moved on might've gotten jobs that greatly or entirely interfere with their time for MUGEN related stuff. Me? I really don't work on the projects much like I used to now cuz of my job and having to look out for my folks at home. After all, MUGEN's just a hobby people enjoy to the point where they'll tire out of it and move on to something else.
As far as sprite sheets goes... it's extremely expensive to order a set of good sprites for a character that has never been made into a 2D fighter before. As for free spritesheets, mostly chibi sized sprites but many sheets don't have said fighter as a 4-6 button character and have only a few attacks you just need to work around.
I really don't have anything to say much about "lazy" content. I've been seeing a few decent releases lately. Life as a MUGENite begins to suck once you actually get a job and have responsibilities as a human being to follow because you can't do what you like to enjoy like you used to.
Beware the Dark Wolf once more!