If apple would have decided to go with flash I think they would have to compromise on battery performance. They did ask adobe to give them a less power hungry, more stable flash build for ipad, which they didn't. Anyone who uses an apple computer will tell you how ridiculous it is to play flash videos (or anything) on a mac. Your machine will go on hyper-drive, and your browser will crash frequently.
Adobe has a history of working slowly on flash, which had horrible stability along all platforms not too long ago, while its definitely much better on Windows in recent times, it didn't improve much on OSX. Their next release for mobile is already delayed twice AFAIK. I think this speaks volumes about Adobe software development. I am hardly an apple apologist, but if there is anyone to be blamed for the omission of flash on ipad, its adobe.
iPhone was released 3 years ago, and Adobe still doesn't have a good flash player for mobile or mac.