Simulators/modellers can be funny things. Sometimes they sound magical, while other times they're dogshit awful. I suspect that's why you get so many conflicting opinions on their utility, quality and usefulness.
I can tell you from personal experience that the amps and speakers/cabs you use can make worlds of difference. Even the venerable Kemper and AxeFx units can be made to sound terrible if improperly applied. But, when done right, they're magical. The AxeFx has gotten so good, it's passing blind taste tests. But, aside from its accuracy, the success of the tests are largely due to the speakers and IR profiles being used.
I think guitars/basses have been pretty well sussed out. I also think the days of the "boutique" or "vintage" amp are numbered in the low digits. What people have to learn now is the rest of the chain. That is, the reproduction end. Power amps and speakers. Get those right, and you've got nothing to cry about but your own ability. Even Metallica, Alex Lifeson, Steve Vai and many other pros are using AxeFx units now in lieu of their refrigerator-size sfx racks, so that's gotta tell you something.