I've used Sketchup for a long time, and I know how to properly employ its tools. And so far, it doesn't seem like it's "a single user". And as a programmer, I know that this feature would be simple to implement, unless the code was a nightmare.
Edit: I see several users so far rail against me for suggesting a very simple feature addition (something that wouldn't affect these users at all if they chose not to use it), assuming way too much about the code base and other things, cutting very close to personal attacks. Please, stop it.