Would you prefer that they include Christmas/Easter/Halloween themes when that time of year comes like other MMOs or would you prefer that they didn't?

No i don't. When i play MMO, i wanna slay bandits, dragons and fight with other players in PVP. I don't care about real life festivals in game.

Personally I would not.

I do like the idea of holidays, but I would love them to be connected to Tamriel. Simply for variety I already celebrate in the real world for the festivals I care about so why not add something completely different in game? Add celebrations that have no relation at all to our holidays and go for new and lore fitting.

Also I would like them to be far more infrequent then certain other games. A fortnight every quarter for instance, rather than seeming to overlap in othe games so there is so few times when the world is just normal.

I dont mind ingame related festivals - like, i dont know a "Day of the Emporer". At least most cultures, no matter what time, had some kind of annual festival(s).

What i don't like to see is something like Orcs dancing around a giant christmas tree during christmas, or pumkins all over the place during halloween.

I'd rather gnaw on my dead bone than experience another real life festival in an MMO...

Well in lore there are festivals, they've just never taken place in the TES games before. The best example I can give you is Saturalia which is a type of Christmas. If you've been paying attention to the latest mods popping up on the Skyrim Nexus Mod page you might have seen it at Christmas. http://skyrim.nexusmods.com/mods/28093

There are also all kind of different events and festivals through the months in the lore including the summoning days of daedra: http://www.uesp.net/wiki/Lore:Calendar