This is definitely why we do a beta test. We can also do things like reset the realm at a busy time like 4:30pm PDT to try and find the source of a certain issue where a crocolisk is losing it’s brain due to how multiple processes are interacting and mirroring code to form a cohesive world. There were similar types of issues like this back in 2004 but we wanted to try and resolve this one before the weekend for the folks who are testing. (Blue Tracker / Official Forums)
Things like Tauren melee reach being bigger, which is something I experienced going away live during Black Temple Illidan progression (at least for that particular encounter), is confusing to players as it's a significant advantage over other races in some instances. No quest tracking is another apparently confusing issue, as many Mankirk's WIfe seekers well know, and there's a whole lot more where that came from:
I recreated my very first character -- a human warrior, because in the last-push alpha test I joined in 2004, there was no Horde -- and logged in. Immediately, I was surprised by how good the graphics actually looked, for being 15 year old textures-on-polygons. Warcraft's bright colors and cartoony aesthetic continue to this day, so all the increased resolution and better-contoured characters in Lordaeron don't really change the game's visual aesthetic.