Chen Zen, I would normally agree with you if we were considering any MA other than TKD. However, I think that in the case of TKD, it is so focussed on kicking and sparring that a careful analysis of the Poomsae will benefit most students. There are numerous hand techniques, including a lot of clinch work and a few unorthodox throws (e.g. the "knee break" in Koryo, which is more practical as a throw) which round out the style very well. Most people ignore these, which I think is a pity.
I still think that these techniques are only really useful if you have cross training in a grappling MA, otherwise getting them to work would be very hit-and-miss. Understanding balance, gripping and being able to unbalance your opponent are missing entirely from the TKD Poomsae. As is training with resistance, as you said.
(Website by Marc MacYoung, not me)