You have to admit that Glock was the first of it's kind in handguns. Now just about everyone has some kind of polymer gun. People have a lot of choices and we gun owners always want to try the latest and greatest thing.
I think that because they were the first that everyone knows the name and tries one. Then when they don't like it or get tired of it, they sell it off and try another brand.
PSST... h&k was the first plastic handgun...
Mike