it seems to me that investors might feel more comfortable raising the commission even higher, so that the lump sum is not so much more attractive than continuing the business.
however, the low rates may be just to attract early investors. additionally there may be a 'reputation cost' when running away with the coins what might swings the figures.
The initial 1% rate was just picked at random. I had no idea how much would be wagered, or what it would cost to run the site in terms of time and money. It turns out it costs all available time, and prevents me from working on anything else. So I suspect that the 5% rate is going to have to go up in time so I can continue to support myself.
For the time being however I want to keep the rate low to attract investors - a loss-leader if you will. If it's too low and is actually scaring potential investors away then it's no good - I'm taking less than I could AND hurting the site at the same time.
The reason I don't run away with the money is (a) I'm not a thief and (b) I don't want to have to be looking over my shoulder for the rest of my life. (c) "my bitcointalk rep" doesn't really come into it. I'm amazed and flattered that people are willing to trust me so much, and won't abuse that trust. But if I was a scammer, a million dollars would be worth destroying my reputation for I'm sure. Luckily for everyone, I'm not.
I like the idea of split key or shared key use.