I know you've probably never been exposed to it, but GG2's ctf is a lot of fun for me to watch. Of course it's not going to be a tactical masterpiece like watching 5cp is, but there's going to be plenty of entertaining flag grab attempts and combat tactics for some casual commentary. CTF is a naturally DM oriented gamemode, and that doesn't have to mean that it's boring and slow. But, there are push pull mechanics and attempted caps just like TF2's 5cp, and if I had to compare them then GG2's action is considerably more constant than TF2's thanks to faster spawntimes and there being no reason to hold stalemates. I feel like TF2's CTF could work the same way with a map designed around mobility and holding onto two paths instead of just one (turbine...).
For reference, here's a mid level video of one of gg2's best players in a 4v4: http://www.youtube.com/watch?v=PQwBm60Bjlk
It's probably one of the slower matches I've watched, because of the massive pussyfooting both teams were doing and the clutches he kept pulling when his team was dead, and the respawn times being too fast. The pussyfooting was because it went down to two caps very early with an unusually long time limit. The cap limit is high for an equal skill match, too, 5's usually for uneven footing. I know it's all tangential, but honestly I just don't think you know a lot about CTF to say that the action always feels meaningless with no exception; either that or you're bitter vs it for some reason. Used to large numbers of players in small maps?
I don't think you can speak for every game with CTF being boring to watch in general, either, as I absolutely love watching Q3/QL and TFC CTF. I just don't know enough about them to make walls of text like I already am about GG2.