Well, yes, they could. The reason I'm recording my tweets to LJ is a much more selfish one: i.e., I like to look back on them in bulk after the fact and reflect on them, to see if there are any off-the-cuff ideas or comments that could be fleshed out later into more full thoughts that would warrant writing about here or elsewhere.
It also helps me "hold on" to links and such that I might want to revisit at a later date, as well. Twitter feeds evaporate over time, but LJ posts last at least a little longer.
So, long answer short, I'm crossposting 'em here for my own use, rather than for my readers per se. By all means, if you don't care for tweets, skip right on over them with my blessing. You probably won't be missing much. ;)