Is it bad I wish Lucas got out after the prequels so Legends got mainstreamed?
Matter of taste. I personally prefer the pre-TCW Legends continuity to what came after Lucas and Filoni got into it, but it's not really good or bad.
Though if you want to be cynical, Legends
did get mainstreamed. Just not the parts anyone was asking for. We got big-screen adaptations/rip-offs of Dark Empire and the Darth Caedus arc, which even Legends fans were mixed about (at best). And for good measure, Disney's inflated the Mandalorians in importance far beyond even Karen Traviss on a bad day. /rant
But ITTL, of course, none of that exists. The phantom "fourth original Star Wars movie" is going to make the post-Endor galaxy unrecognizable, and we won't have Zahn or anyone like him--and since a Luke going dark arc happened on the big screen, Dark Empire won't happen either. Heck, if Leia's not going to be Luke's sister (that was kind of done last-minute IOTL because Lucas had the dangling plot thread of the other Skywalker, wanted to make Luke's sister a subject for future films, but lost interest, so he just made Leia it to tie off that thread and end the love triangle too), then Harrison Ford probably gets his wish to have Han die heroically and we end up with Luke and Leia paired off.
Actually, on a franchise history and cinema history level, I wonder what effects this might have more broadly. Lucas keeps making Star Wars movies in the 1980s--probably means less involvement in Indiana Jones? Which might mean no Young Indiana Jones chronicles down the line--and that was one of the things that made him more open to a prequel series. So probably no Prequel Trilogy at all ITTL.
(EDIT: IOTL, Star Wars was retitled "Episode IV: A New Hope" in 1981, so the plan for the prequels was already there, as was the trilogy format; this implies that Episode VI
is followed by a sequel trilogy of VII-IX, featuring Luke's sister and presumably a plot around bringing Luke back from the dark, and a long-term plan to make prequels, assuming that 15 years worth of butterflies don't change that retitling)