The single thing Altium really had going for it was that it had sort of become a lingua franca of sharable designs. And engineers, being the lazy shits they are, would simply pack up the library and ship it with the schematics. Consequently, you got an actual, engineering validated symbol and layout when a company gave you schematics.
Once Altium changed such that you could ship a library that couldn't be extracted from, they lost the only thing that really set them apart from the competition.
All the cloud and parts management crap was just insult to injury after that.
KiCAD is good enough for all but the most demanding commercial use at this point. It has some quirks, but all CAD programs do. Every major release has been a big step forward. Version 7 was a huge step up, and they're about to release Version 8.
The biggest issues with KiCad would be using them for very complex designs: huge numbers of length-matched busses (think desktop computer motherboards), weird flex designs that need combined electro-mechanical CAD, so many signals that you need a complex autorouter, extremely advanced inventory management, etc.