I thought ths same thing when I went from SPDs to Keos. I even went back to the shop almost in tears. They explained that they're purposely weighted like that and that I just needed to get used to them. As you start from a stopped position, the pressure from your foot will level the pedal at the same time as it engages the cleat. It really comes down to timing and having a sense where the pedal is. The best advice I can offer is to practice. Go to a parking lot and do it over and over again. You will soon get a feel for it. I still have trouble here and there, but it has more to do with operator error than the pedals.
Also, there's an article by Chris Carmichael someone linked to in another thread about clipless pedals recently. You might do a search for it. I would do it myself but I'm on my Blackberry at the moment and it's not as easy to do as on a PC.
As for the tension, I just got a new set of Keos Sprints for my new bike. With the tension at the lowest setting, they are almost too loose. You really shouldn't be having a problem in that regard. You do have to apply some pressure to engage the cleat, however.
Good luck! Think of it this way. Keo pedals wouldn't have the market share it has if the pedals truly were impossible to use. So don't give up just yet!
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher