The issue is this: "how much does it help or hurt, by practicing or not"?
The answer is complicated for sure and no one really knows. Now the way I look at it something like this... Take WR as the example. There are many players in the chain of events for making a catch or missing one. The HANDS factor of the WR is only a small part of that chain. The QB has to first be a decent QB in order to make a good throw. Then he also has to have TIME to pass, in order to make a good throw (so the OL comes into play). Next the WR has to be OPEN in order to be in position to make a catch, the DEFENDER has to be in a poor position so as to not interfere with the catch, and finally.....the WR is gonna have a chance to make the catch. At this point a WR with hands of 10 vs hands of 50 is not that much different.....when all of those things are factored in. So....perhaps a WR with great hands will make up for some shortcomings in the earlier parts of the chain (meaning his ability to make a catch even if its a bad throw), but even then you have the WRs TECH and ATH coming into play.
Even after all of that, you have to think about the kind of offense you run.....deep passes which are theoretically more difficult to complete? or the short passing game with higher probability of completions?
So to say hands does not matter is probably an overstatement, but to be able to figure out exactly how much it factors in, is impossible. I think this is one of the key complaints about the current engine...you dont get enough information in the PBP or otherwise to know what is really happening. If you had a WR that had several "drops" and the PBP always referenced "hands of stone"....you could possibly determine that you needed to have improved hands rating for that player. On the other hand if the PBP always referenced "broken up by the defender playing closely"...then you might not care about improving the hands rating of your WRs...
Personally, I practice hands for my WRs, TEs, RBs, QBs. However, I NEVER look at hands for recruiting. In the spirit of full disclosure, this is D3 I'm talking about. At my D3 team I toss that pumpkin quite a bit. At the higher levels I only run the Wishbone, so my focus is not on the passing game anyway.