1) Identify- Pretty lousy spell because of the component, but sometimes you gotta do what you just gotta do. When selecting domains, pick another domain with a good first-level spell (like Plant, Strength, or Water).
2) Detect Thoughts- Situationally useful, but if you apply it creatively then you can make it more useful more often.
3) Clairaudience/Clairvoyance- Your first scrying spell. Until someone gets Scry Location, this spell will have a purpose.
4) Divination- More limited than Commune in that you only get one question, but substantially easier to use because it's got a cheap material component instead of an XP component (and it's a level earlier). Honestly, I always prepare this in my Domain slot.
5) True Seeing- If you need it, you need it. I agree that this is a weak level, though, so pick a complimentary domain with a strong 5th-level spell (like Earth, Plant, Magic, or Protection domains).
6) Find the Path- Probably the best divination spell ever. Find the exact route to a destination, and automatically find all natural hazards and traps along the way.
7) Legend Lore- It's tough to justify at 7th level, but it's a worthwhile cast if you need information, and at the very least you have access to the spell when you need it. Again, pick a complimentary domain, because you aren't going to cast this spell all that often (Protection and Magic are good again, as are Water and the Alignment domains).
8) Discern Location- Like Detect Thoughts, it's situationally useful, but it becomes more useful more often if you are creative with it.
9) Foresight- As a 9th-level spell, I have to agree that it's underwhelming. If you aren't immune to surprise by some other means, however (such as Divine Oracle 10), then this is not a bad place to get it. Frankly, few domains have a top-of-the-line 9th-level spell, anyway.
So no, not every spell in the Knowledge domain is a rock star, but no domain is like that (well, except for Spell and Time... Mystra is brokzorrs). Knowledge has a lot of really good spells in it, and the ability is really good as well. Compare that to Inquisiton, which is really bad in terms of Spells and only has a good ability if you're grabbing Sor/Wiz dispels via Divine Magician (or you are a Sor/Wiz), and it's clear which one wins.