This is actually a good move. Bledsoe is an unproven talent on a position they have mostly filled in, and with the cap being what it is, overpaying is not longer the right thing to do. They did that with Frye's previous deal and he became untradeable.
If Bledsoe would be as good as he thinks he is, he would've gotten a Parsons-level offer sheet, which would make it very difficult for the Suns to match (not necessarily monetarily, but because they pretty much already signed his replacement).
To me, it's interesting that both in the Clippers and now the Suns, Bledsoe has been a trade chip. A guy that is not good enough to earn the starting spot on his position, but has enough 'upside' hype that he becomes a good asset.
The easiest way to solve this for him is to play for the QO this season, put a solid season together, and then go into unrestricted free agency next season.