To me someone who is not a developer or a themer, just someone who likes to try and make his phone better by what others have done, the bootloader being encrypted really has no effect on me. I am overclocked, undervolted, with a custom ROM and theme. Now when I first got my X I was happy with it out of the box, then I rooted it so I could get the leak of 2.2. Then after a few weeks added a theme, then added a ROM. I would guess if the bootloader was not encrypted I would be doing more as well, but it has not hurt me.
My bigger concern on a phone will be what is the development community going to be like. My wife got the D2G, they were not selling just the D2 anymore and there is virtually no development for it so she is stuck on just a rooted version of FroYo at this point. So if the development community is not going to support a phone with an encrypted bootloader this will be an issue to me. The Droid X has had such a huge following this has not been an issue, but since the X there has not been another Motorola phone with this much support, maybe the Bionic will have it, but it may not as well.