I suppose 'first love' syndrom has a lot to do with it with most here, myself I did happen to start on Red Moon as my very first MMORPG but that was for like half a year in 2001 - the game felt a bit too fast, too risky, too arcade like for my liking, also it suffered from poor updating from Korean parent company LOL and when I heard ingame that some online game called LoM is opening new server in September I decided to go have a look at it and stayed next what, eight yrs counting? Plus about one year of mir usa.
Never liked 3d game view, IMO 2d isometric of the mir2 flavor is just right, you really don't need more for game enjoyment, at least of the sort mir provides. Its too bad mir3 split off, I'd rather see they kept mir2 looks and gameplay and just kept adding to it to make it bigger and newer on the perimeter, inside which new pple would always find those old original lands of mir2. I did try mir3 couple times but stayed just a day or two and came back to original mir. Mir3 had smaller character and items in bag or on avatar looked too big, just to mention game looks, the feel was also different for no good reason.
I guess it all comes down to familiarity with what you got to know over all those years playing and it feels like being at home whenever you log on.