SCAG is fine but isn't as comprehensive as the old setting guides for 1st, 2nd, or 3rd edition.
The lack of gloriously packed boxed sets for settings is my biggest gripe with WotC's management of the D&D brand. I'm sure another publisher could put out lovingly detailed campaign settings and turn a profit (which would be shared with WotC, as the licensor).
I'd imagine that Kickstarters for boxed sets of beloved settings like Greyhawk, Forgotten Realms, Planescape, Dark Sun, etc. would be well-received and funded. While there are are many who wouldn't be interested in such products; there are also plenty of middle-aged nerds (like me) who'd love them and buy them all!