Warcraft to me I think will always be a nostalgia trip that one can never truly replicate. Its a bushy eyed kid who rolled an orc hunter on his neighbors computer in 2008 and was swept away by the fact there was a game so massive that it would take a literal day to only travel from one end of the world to the other. Watching him go raid Sunwell and then hop into AV to grind out some honor and just beat out everyone as a ret pali. Unfortunately, he was Alliance 
But to that end, Warcraft is the world and setting that was developed from WC3-Wrath/Cata. To me its the exploration, adventure, and curiosity of Kalimdor and the Eastern Kingdoms. It is an orc, troll, or tauren stumbling upon Ashenvale for the first time and getting lost in its canopy, trying to figure out where you’re at, after questing in expansive, flat, bare, land for the past 20 levels. Its the poor Forsaken who went to the Bulwark instead of Silverpine, just to be mauled by a lv 40 bear.
It is this unique and, for the time, relative progressive take on the fantasy genre that turned many tropes on their head. It isn’t so much the larger narrative arch rather than the isolated zones and stories that are told within them.
Its being introduced to this quite troubled, but trying, society you find yourself apart of that makes you feel as if you’re the good guy in your own story - or at least not the mustached villain. The bad things you do are an unfortunate need for your people to survive, or maybe you should give a deeper look into why you’re killing a whole bunch of red bandana wearing union strikers for a king? Maybe some of these folks had a point. Its grounded.
So when I hear this “doesn’t feel like Warcraft” from folks I hear “it no longer gives me a curiosity that connects me to my character, world, or friends.” At least thats the optimistic view of it. That one does not feel connected to the setting, their character, or people they chose to play with when they started. That this poor stick and mud orc who was just killing some boars in the desert, looking for this mans poor wife, getting lost in Ashenvale, and being apart of this months long campaign to unlock and assault an Old God fortress with your faction’s champion and hundreds of other players, in the finest armor one could find, is now on this stainless steel magic space ship beating a demon 10x their size to death with a couple rolling pins wearing a plate-kini cause this other horned half demon elf thing wanted to go on a magic school bus trip, or god forbid facing off against robo-devil.
The more pessimistic side is that this game no longer caters to their old school delusions that this is somehow a grim dark 40k game where they can simultaneously can act out their worst Dark Eldar fantasies while going Deus Vult and yelling slurs into Vent cause the 11 year old hunter in their 2nd raid stood in the fire for half a second when they themselves haven’t kicked a single spell they needed to and doomed the group from the start while being bottom in damage.