Making great music and being such a badass live band is an accomplishment in itself, whether record sales followed or not. They could have released Back In Black and if it was on Sanctuary Records, it wasn't going to sell. That label is fortunately long gone now.
Nobody mentioned huge tour opportunities - however, everytime they came through Ohio, both headlining and not, the shows were completely packed (Toledo being the one exception - but they had never played there in their entire career, before or since - so they never built up a fanbase - and people from Detroit didn't make the drive because it was a Tuesday night). Other than that one show, the shows were packed - maybe not 100% sold out but so what? Yeah, they were club shows - but even bands who sell a lot of records such as Disturbed play clubs...it takes a bunch of big bands together to play an arena anymore. You could have a number one single and still be playing clubs. It's the nature of the industry. And what shows did the reunion have that were any bigger than the WCFYA tour? None. Sure, they played some big festivals overseas - but they always play those festivals overseas. They did on the WCFYA tour. Even smaller bands do.