I can understand where the complaints come from, and I understand why spawn camping is a valid tactic. Just because it can ruin a few peoples experience under constant use doesn't negate its validity.
I like TF2 because of the freedom of movement I have as most of my classes. The only problem a long duration marathon of spawn camping gives me is that my "freedom of movement" becomes 3 person wide, long hallway that one heavy or one demo turns into the ultimate easy mode death trap.
I don't mind being the target of spawn camping every now and then, but when you have people that do it every single life, and then teleporters come into play, 3 heavies, 4 medics... You try having fun when its a 20 minute marathon of camping and the only path you can take is the longest choke point. Then uber+instant respawn+teleporters = that heavy you just took out in his 450 HP + 20hp/secregen glory came back 3 seconds later. Its not really a game anymore at this point, its just meat grinder mode.
And because that scenario happened to me, now I memorize people's names so I can identify the constant spawn campers and single them out to attempt to minimize the damage they do to the team and morale...
If you want waved respawn, you can't do it on the current blackmesa. You'd have to make exiting the spawn safer like almost every valve map does. Otherwise spawn camping just becomes that much more demoralizing and effective.
The current instant respawn system makes the map a wonderful battleground in every other part of the map however. And if you took waved respawn in, the map would feel that much more empty even with 32 players.