In all fairness to Valve, HL was delayed almost as badly, because they finished it more than a year before it was released, then started all over again because it did not meet their expectations.  I doubt anyone would now second-guess their decision, because they ultimately turned out maybe the best game of all time.
TF2 was initially conceived as a free add-on to HL, but along the way their plans got more and more elaborate and it turned into a stand-alone product, then into the most ambitious multiplayer shooter ever.  Now they are creating a new engine for TF2, so significant delays were inevitable.  Meanwhile, TFC is essentially what they promised early on for TF2; a very good free update of TF with the HL engine.  Of course I never play it 

 because CS is about a million times more fun, at least to me.
If you want to hear me bitch about a very promising shooter whose delays are absurd, get me started on Duke Nukem Forever!