The faceroll aspect is one of the main reasons I can't stand current retail. One shotting mobs now from the start?? Ridiculous.
I was never a fan of levelling either way - I used to find it tedious in general but it was okay when you would face some challenges along the way to make things interesting. Making mobs trivial, the removal of elite quests and mobs, the fact that by the time I quit retail lots of people had multiple max level characters leaving the early zones beyond dead.... you are literally clicking your attack button and facerolling to max level all on your goddamn own.
Then this continued into everything else.. dungeons, max level quests, lfr etc. Top end raiding might still be difficult but a lot of people will never see that and either way destroying the rest of the game in this fashion is not okay with me. My last attempt levelling in retail I was soloing dungeons to find some sort of challenge... what should not be trivial for a group of 5 has become possible for 1 alone.
Levelling on Nostalrius was a joy. Within the first few levels I was struggling on a quest and ended up grouping with someone I saved from death to make it easier. Personally I loved the high population and the challenges / opportunities it could bring. 12k maybe too much but it certainly made me feel like the original games server caps were too low.
You say this faceroll is just at low levels but I don't buy that at all. Playing Nostalrius caused me to look into resubscribing to retail. I was reading up on legion and came across a video of a mage completing the quest chain for the artifact weapon. The guy kills the boss for the last part of it without losing any hp or mana what so ever. After seeing that all thoughts of resubscribing were gone.