They're a great idea on paper for these reasons. With long cooldowns compared to how long battles last, and exceedingly long ones for the good shouts that shut down your ability to use lesser ones, the implementation is lacking.
I can see that point to a certain degree- with single mobs and low level groups like wolves a single shout can seem almost worthless. And once you reach the 'soft' level cap area, almost every enemy is pretty easy to defeat.
However I would also pose that again, this is a new mechanic and I don't think Bethesda really understood how
fast people were going to level in this game- people were level 50 in the first month of release. Whether that is because game mechanics are broken and levelling is too easy, or the devs honestly thought people would spend more time exploring, hanging about town, etc...I don't know. But I think now that they have some ideas of how people are using the game, they will implement things in patches or in the expansion to more fully flesh out the shouts and other combat mechanics.