What's wrong with evolution- its human nature (at least here in the West) for people to try and move things forward. Nothing can hold to tradition forever. Everything falls apart in the end. Things that are unable to change get left behind and are of no interest to the next generation. It is to Aikidos credit that it is being evolved. This shows new generations are interested in it and can see its relevance.
I can't think of many things that have stayed the way they always were that are still looked upon are useful and relevant. They are normally thought of as against rational thought and enlightened progress. Examples are fundamentalist religion, creationism, communism and doing reverse punches from the hip while standing in a deep horse stance. You cannot want aikido to come to this.
The important thing for aikido is to maintain the essential ideas that made it good in the first place- centredness, breathing, relaxed power, flow- and adapt them for the current climate in martial arts. In my opinion this should involve more interaction with the martial arts community at large through mixed training and sparring etc, but this doesn't seem a popular idea.