Basically, because what is being sought is a quantum theory of gravity

Ah, that makes more sense. I must admit, emotionally, I find it hard to believe
that we'll ever find the 'one' theory to explain everything. (Hope that doesn't
put me in the neo-Luddite camp lol)

Also, your impression of a particle "zoo" is not quite accurate.

Sorry, I was being lazy. :-(

Thanks for the answer. I hadn't made that connection. It makes more sense when
approached from the quantum view.