They don't have to be weaker. They should be as good as at least your secondary, but offer something your AT/sets do not offer. Like the majority of AT/sets do not have travel powers, so pool powers offer you choices for one or more if you want. The movement option are not lesser than your sets powers, but offer you something beyond your AT/sets.
The other pool powers should reflect the travel power design and be just as good, but offer you choices your primary and secondary do not. A good portion of the pool powers do this somewhat though they could use some tweaking. I could see the different attacks in a pool power be as good at the minimum of your T1 attack and be as good as your T2 attack.