The risk is any young pitcher can get hurt. But, at least, we went college pitcher. However, you can never be too sure. But look at the increased risks of HS pitchers. For every Beckett there are two Taylors
Honestly, it isn't as if FA pitchers are knocking down the door to come here. As such, the Rays have to develop their own or trade for it, and this off-season has shown how teams value young pitching. You can't simply draft offense only. So one got hurt, that doesn't mean you stop drafting pitchers.
As for Townsend specifically, I'm not a scout. But I only read good things about him in pretty much every publication before he was drafted. While it doesn't guarantee success, it isn't as if the Rays were alone in their high opinion of him.