I suppose because it would make hitting level 60 feel like an accomplishment. That's what has died in current MMOs is that feeling, but it is because of the time it takes, and obviously would cater to a different type of gamer. However, I do understand the need for 15x if that is what makes the server active. It just doesn't register to me though because if you want to play a game in it's natural, original state, that just clearly defeats the purpose, besides being free, which in the tough economic times we are in, I can understand as well.
Also I assume it's a pvp server? I believe a lot of people may have started with the 1x leveling, gotten PK'ed a few times, said "eff this" immediately turned on 15x. Too much player power in my opinion, completely giving in to that McMMO effect that is widespread and rampant.
However! Props to the devs in creating an active server which I could see many people enjoy. I don't believe I will be partaking though. Good luck and have fun.
trust me, you enjoy a lot less immersion of the original game in 1x underdeveloped servers than here, probably the most advanced one. So i really suggest you to partake despite the option for 15x or 1x , sure it felt as an accomplishment back then and still does to level all the way with 1x, but for a brief moment as truly the game only begins at that point, and in my opinion the accomplishment feeling of reaching 60 like that can by no means overcome the quality demand of endgame which your basically setting completely as secondary factor when you roll on any of those small servers, or even on the biggest one if youve for one seen their naxx scripting quality as comparison