Obviously if I'm a rebuilding team, I want the draft pushed as far back as possible. The main reason being that with already cramped farms/picks:
a) I get more time to see who is legit/who I should be letting go
I get more time to make a trade to clear space
I like that pushing it back would give more security with your picks. What I don't like is that it will be significantly harder to find gems in our draft. By August, players will have played over 80% of their season. All the midseason rankings will be out, and everyone will have a pretty clear cut value heading into 2015. I like how everything is more ambiguous in June. You get rewarded for doing your research.
I don't think that many people got bit by non-signings last year. If you did, you still have the option of holding onto the player. Plus, as someone else mentioned, you can factor signability into your MiLB pick giving it most realism anyway.