Jerry Rice's numbers were a product of his place and time. So were Hutson's. What would either have done in the other's era and with the other's team? Who knows? Probably they'd both have still put up better numbers than anyone else.
The problem with football in general for arguments like this is that the statistics are so far more skewed than they are in baseball.
Rice (as well as Montana) benefited greatly by playing for Bill Walsh when he was the first to really build an offense around the huge rules changes that occurred before their 80's heyday. If they'd tried to run the same exact offense with the same exact players in the 70's against, say, the Steelers, they would have gotten their hats handed to them. Limiting the contact on receivers, allowing the use of hands for OL, all these were huge changes that allowed the timing passes the Niners made famous. Without those rules, about 2/3rds of Rice's slant patterns would have sailed incomplete because he would have been knocked off his route by multiple defenders before he got there - and Mean Joe Greene would have run right over Randy Cross's leg-whip to bury Joe Montana on his 3-step drop... And because the Niners were the first to embrace that offensive system, every defense they played had been built to stop something completely different. Once a certain number of teams around the league had adopted substantial parts of that offense, defenses were built to stop it, and you had those years where Fritz Shurmur's defense made the 49er's look pretty foolish.
So basically, a lot of the advantages that Hutson enjoyed as a receiver in the most pass-happy offense of his time, Rice also enjoyed playing in the West Coast offense. So Hutson led the league in long passes, Rice led the league in 2-yard TD passes because the Niners were not going to run it in from there...
And, since everybody's jumped on this Paul Warfield thing - he played in run-heavy offenses his entire career. Having watched him play, I believe he would have been every bit as good as Jerry Rice in the 80's SF offense. That's strictly opinion, of course, based only on watching (and rooting against) him... I also think Lofton was better than Rice in his prime.
Another name I'd throw out there, without any great stats to back it up - Otis Taylor.