I think the "haters" you are referring to are more so upset about the fact that they advertise that their core is "much better" than the Nostalrius core (it's actually much much worse), also while advertising that the experience will be the same as it was on Nostalrius (it very much isn't).
I think the frustration only stems from the expectation that this was going to be the exact same as Nostalrius, just happening all over again. The sad truth is that the VanillaGaming folks are simply incomparable to the Nostalrius folks. In terms of being professional, experienced, and having the developmental know-how of running a good server.
Most of the players on this server (according to Nostalrius data) are NOT players from the old Nostalrius server. The players from the old Nost are upset because this server is in fact quite shitty compared to the original, but it is all we have, so deal with it or simply don't play on it.
VanillaGaming has existed for many many years, and their old server had only a few hundred players at most, was quite unpopular, and was ridden with unplayable bugs. The people following the Nostalrius craze don't know this about them, so they expect much more.
