You know this complete and total anecdotal and just a person opinion, but I still feel like Blizzard have made a big mistake rushing out BfA, and it does feel rushed for sure. I know they want to avoid things like 13 month Siege of Org stale content and they have constantly promised to release content faster even though that is hit or miss really. Legion was obviously worked on a decent amount and you could tell by how smooth the launch was, the pre-patch was smooth even if the event had some fucked scaling issues.
BfA is the first expansion that they announced a release date on so early almost a year ahead of time. You hear about issues with BfA from the beta testers that things feel uninspired and unfinished. They say the talents are pretty much garbage with the artifact necklace and there are some serious problems with class design or lack there of knowing that some classes aren't even getting a pass until 8.1 admitted by the Dev's themselves. It really feel's like this needs a few more months of polish and they should of never promised a specific release date. If they took a couple months to finish up and test all this shit down to the stat squish and old world scaling I feel like it would be worth it. Delaying this until October or even November wouldn't of been a big deal if it meant that was released in a polished state.