I was reading an article (I think in Black Belt) some time ago about one of these new martial arts that use techniques from lots of other martial arts and add them up into a big mix of things. In that art, the person who created it had supposedly absorbed Aikido techinques into his "medium range" strategy. In other words, there are other MA which will be more effective if you want to kick someone's rear up very close, or grappling, or on the floor, or even farther away, but Aikido was deemed effective for just about the range we use it for.
As I understand it, Aikido is effective mostly against a dedicated ("lunging") attack because any attack which is not fully committed is dealt with by other means than Aikido techniques, like moving out of the way as you said. If someone isn't really committed to attacking you, don't try to force your Aikido on him or her, or you will be risking inflicting harm on him for no good reason, which is against the most basic teachings of Aikido.
Those are my random thoughts.