It seems to me that Academy schools are just a massive experiment by the government to see if they can polarise schools even more. If academy schools actually resulted in attracting more outstanding teachers and headteachers to the profession, developing them and then retaining them, then maybe they would be a good thing, but it doesn't seem to be working that way so far and they've had quite a bit of time, now, to do that.
Moving a school away from LA oversight is not going to make it automatically better, as LAs aren't the cause of bad schools, it's inadequate headteachers and staff who make schools bad. LAs can only have general oversight to limit the damage and bring things to peoples' attention before it's far too late; the day-to-day running is not in a LA's hands. Academy chains are hugely less accountable than LAs (the government wants to be able to inflict them on local people against their will, they can't be elected in...), and don't make things more free for the inspirational headteachers the government claims it wants to attract - they are often far more prescriptive than any LA would ever have been. Why would an outstanding headteacher want to do what they were told by an academy chain any more than they would want to be told what to do by a LA? As for academy schools that aren't part of a chain - they are more free to mess up big time, largely because they have less oversight, as no school is actually that free, as well as technically more free to improve.
In reality, in my view, academy schools don't have many more genuine freedoms than any other type of school providing state education - the government decides what targets they must meet and what hoops they must jump through (British Values, GCSEs, A-levels, etc), and most parents' desires for their children's education are pretty mainstream, anyway, so they won't want to have a radical experiment of a school inflicted on them when they don't get any of their actual school choices. Basically, the government gives pretend freedoms to schools with one hand and takes them all away again with the other and its only apparent real interest is to find ways to cut funding to LAs. [cynical face]