The trade deadline should be moved back another week at least... Think about how many more players would be dealt when the sellers would have separated themselves even farther from the buyers...
It's been moved back twice already, one week each time. I think this is why we saw so much activity this year, because it became clear to some teams like DEN, PIT, DET etc that it made no sense to hang on to players they weren't going to sign/extend in the off season.
In the case of Claypool I heard the bidding started with a 2nd, because PIT said they were going to get a 3rd for compensation so they might as well keep him for the rest of the year if no one would offer a 2nd. Getting CHI's 2nd seems like good value since overall it should be top-half of the draft.
The old-school NFL did not want to push back the trade deadline. The thought was you should build your team in the off season. If you could shift a major player during the season then the whole construction of the schedule would suffer because a team that used to be strong would now be weak, or vice versa, and that could shift the standings. Of course injuries could do the same thing, but those are out of anybody's control.
The new-school NFL is now mostly concerned about entertainment, so we could see what you want, the deadline shifted even further back.
You could see some strange things if you push it back too far. We really could see a team totally dismantle itself during the season, trading away everything they can trade and finishing out the season with scrubs. We could see a team cherry pick a lot of talent to try to make a playoff push and set themselves up for years of cap hell just to do so. We could see teams say "let's just get to the trade deadline then we can decide to go all in or not". We could see money change hands under the table to enable certain transactions. It seems the NFL just did not want to make this become too big a thing, to remove these kinds of temptations.