I'm beginning to believe what a lot of people are now saying, what's been said since "Return Of The Jedi", even: that Lucas has a beautiful tale worked out in the Star Wars saga, but in terms of executing it as the director... well, this isn't his strong suit. He should have executive produced instead.
Where did you hear of the cut scenes? from trailers and things?
A&E's Biography show is doing Star Wars Biographies this week. Naturally they did Lucas on Monday. They showed Harrison Ford saying that at his first meeting with Lucas for American Grafitti, Lucas encouraged him to get involved with animated film making, since you didn't have to bother working with actors. It looks like Lucas knew what he did best all the way back at the beginning.
I was not as disappointed as you. Not at all. I think you had some expectations for what you wanted to see based on what you knew. I didn't know what was left out, so I was impressed with what was there.
The scenes you talked about may have added some great subtext, but they probably slowed down the action, especially at the beginning. Undoubtedly, some will be added to the DVD.
Lucas cannot direct actors and has a tin ear for dialogue. Notice who does well with Lucas -- experienced actors. But inexperienced actors -- Portman, Christenson, and especially Best -- have trouble with Lucas' lack of direction. As many films as she's been in, Portman is still young. Consider even Hammill. Look at ANH again. He's incredibly whiny ("I was going to go to Taaaaaashi station to pick up some pooowwwwer converters.") Also, note that AOTC (and TPM) have polite introductions. They're slow and boring. A perfect example is in TPM when Anakin meets Obi Wan. Unnecessary. Have them meet in an action sequence.
Lucas is a visionary and he does know the CG technology (which is why he insisted on directing these three). But he can't do the boring chores of directing actors and telling them how to react to what they're facing.
One thing going for GL, he needs no exposition for Ep. III. He can hit the ground running.