Frankly, one of the biggest advantages of having so many codepoints is being able to burn some of them on less-useful shit simply so the standards folk can move on.
I think trademark laws would stop that. I'm not sure, but I don't think anyone else is, either, so the uncertainty would prevent it from happening.
I do see what you're saying, and it would be a slap in the face if a script for a fictional language were standardized before every script for every living language made it in to the standard. However, and this is where you and I differ, I don't really see that much difference between emoticons and other little-used typographical marks living languages sometimes use. Face it: The smiley face is typed a lot more often than the per mil mark (like the percent mark, except 'per thousand' instead of 'per hundred'):
http://en.wikipedia.org/wiki/Per_mil
So the middle finger is rude. People are rude sometimes, and the middle finger is a well-established way of showing that, myths about its origin aside: