Well speaking as an LAE I think it sounds like a good idea. We have a lot of ATC slot delays here (flights to LHR) and the thought of being able to release the ground crew at depature time so they can go and do another job, instead of hanging around waiting for the slot sounds like a good idea. We have straight push backs so I see no problem with the crew doing it themselves. But our problem is ice in the winter. The parking stands are also the last places to be swept in the snow, mainly because there are aircraft parked there! We use TBL tractors for pushback, which have a very low mass, and quite often in winter they cannot get enough friction to get the pushback started. Often I am shovelling grit under their wheels so they can get a grip. Some gates have underfloor heating and these are much better, we need it on the other gates.
I see no problem with unsupervised engine starts. Nearly all pushbacks are performed by loaders, not LAEs, and I can't remember the last time we had an incident which would have been handled better with an LAE on the headset.
I think that airlines that operate to crowded airports where you have to wait in line for departure will find this a must have.
I am definitely for it, hope we can afford the leasing costs!