I had the same problem with Calico, after he got cut from the Titans, no one wanted his cards, which was fine with me. It gave me the opportunity to pick up a lot of nice Calico cards for cheap. I bought a very nice GU/Auto lot from a member on here for $25 DLVD and there were some nice pieces in there.
Do I feel like I lost money on them? Absolutely not. Calico was, at one time, my favorite player to watch on the field and so I'm happy to get some cards of him. Do I collect him anymore? Not really, only if I can find some nice stuff every now and again. His items are actually hard to come by because everyone instantly thinks that no one wants him since he's a bust.
Not often, but, if you can find a solid collector of a player, no matter if they're a free agent or a bench warmer, you can possibly sell them to such collectors. Heck, some collectors buy cards just because they like the way they look, they don't even care who the player is.
Not sure if my rambling helped the topic at hand, but, my advice is that if you liked the players because of who they were or how the played, then there is no reason to stop collecting them just because they got cut from the team they were on or because they never play. Who knows, maybe one of them will explode one year. I mean, I'm sure when Romo's rookie cards and autos came out everyone thought "This guy will be a no-name free agent, he probably won't even make it to the practice squad". Now look at his SP authentic autos, they sell for a grand a piece usually.
You just never know.