Of course you are right that dumping on them is wrong, destructive and irrational. But the bond between fan/program/player is why we love college sports so much, and choose it over the pros.
Goes the same with your comment about the players now being professionals. It's true, they are. But it is a new and very different reality than what made us passionate fans of our school's program. College fans love the program first, the players second and we love them not just for their skill but because they are "ours". And by playing for (and staying with) the school we call "ours", they love us back. Even calling them 'our' players the way you do in your title shows how ingrained the sentiment really is
You're right, that era is over, but our hearts are still running according to the old way. Pretty soon we'll wise up and get used to players coming and going - but it will mark the start of a new, less fun, less passionate, professional era. Might be really bad for college sports. What do you think?