In hindsight, it's really clear to me how much The Sword Coast Adventurer's Guide was WotC putting their foot in the water. This is a supplement that would have sold very well in the 2E era, but standards for utility have gone up. People aren't happy anymore buying a sourcebook and getting just one Feat they'll use, or a single spell. They want to find the whole book useful in some fashion.
I happen to agree. In older campaigns, I had PCs turn their sending stones into a telegraph business, or some such, but like any small start-up, larger concerns should be able to do it better. That's Eberron's whole business aesthetic.
It didn’t really redo dragons all that much. It made dragons an actual species with goals, culture and society though that can be used in a setting. They are the only interesting thing the setting brought for me though. I find Exandria and The Forgotten Realms far more interesting.