It doesn't imo. For how I see it, the MMO aspect strengths are battles, teams, economy, and I don't see how this affect any of these things. I wouldn't say looking for someone to evolve a pokémon is a key aspect of the MMO thing, as it works just like any mainline pokémon game.
If someone doesn't want to interact with people but needs to evolve a pokémon, he/she can still trade with an alt account and keep playing alone. If he/she wants to, the option to do it the old fashioned way is still there. There would be no radical changes regarding this.
These are great points! The social aspect of pokeMMO is very important.
But all of this would still be possible with my idea, and even encouraged because as you said it would save you the fee. And, as you said, it is very easy to find someone who will help you, so in the end it wouldn't change how accessible trade evolutions are. I wouldn't say the main purpose of friends and teams is evolving pokémon. Personally, I don't think someone who dislikes socializing would change his/her mind just to have a Golem or a Conkeldurr.
Just compare the two things:
-you have to evolve a pokémon, so the first thing is asking someone, then meet him/her, then you both would have to interrupt whatever you were doing for a trade that doesn't involve much social interaction
-you have to evolve a pokémon, you fly to wherever the NPC will be, you evolve it and you have more time to do things, even actual social things.
The only downside I see is that it may take developer time (maybe not much, but I don't know how hard it would be to implement) that could be used for more important things because, as I said, this would change very little in the game.