The way I currently play, I raid with my guild, run LFR occasionally (not very often) or queue for some dungeons either solo or with some Real ID/Battletag friends, do some retro raiding in the same fashion, and in general to me my server is almost completely meaningless. I play with and chat with people from all over the place, from Sisters of Elune to Norgannon to Malfurion to Kilrogg. If I could add EU players and chat with them, I'd have an even bigger friend's list. The people I know in game are people I've played with, people I've chatted with online for a while, but in very few cases are they people I've actually met here on my current server outside of guilds I've joined.
Of course, as I've argued before, personal experience isn't universal and anecdotal data isn't conclusive. I'm just one player. So the question becomes, what about you reading this now? How important is your server to you? It's very possible there are thriving server communities out there that would be damaged by a change that reduces server identity further and if so I think it would be useful to find out. If a single mega-server per region would be detrimental to people's playstyles, let us hear you. Positive or negative, your feedback is desired.