I think the tribute concert is a genuine part of the way jazz is today - the classic era was half a century ago and a fresh take on the great achievements of the mid-20th century, as well as scholarly study in colleges today of what was achieved then, is a natural feature of this postmodern age, whether you're talking jazz, architecture, movies, popular culture or whatever.
I certainly agree that tribute activity is a marketing device and a hook, as Bev notes. I recall the leader of the the Tubby Hayes Memorial Band saying, "We're called that 'cos no one's heard of us".