It doesn't matter how athletes get into XC.
What matters is what they do once they're in XC.
I can think of at least 10 local athletes who were plucked out of gym or PE and became awesome runners (sub-15 guys, sub-19 girls).
As for overall interest, today's computer playing/xbox playing/texting all-day generation probably sees getting up and going to the refrigerator as exercise. It's not hard to figure out that the idea of running 3-10 miles a day is not popular amongst that crowd.
And I hate to break it to the OP, but XC has never been terribly popular. Teams today are larger than they used to be, so the interest level is fine.
If you need to be patted on the back by your schoolmates in order to get excited about running, then you're probably not cut out to be a runner anyway.