I think this is a completely fair point. Things in mathematics are astoundingly interconnected and you never know whether a seemingly benign proof will turn out to be the key to unlocking something much more pivotal.

Proving the absence of something lies in the nether regions of science and mathematics. Consider the problem of proving the absence of Bigfoot -- it can't be done. This is a well-understood logical problem with a storied past:

http://en.wikipedia.org/wiki/Russell's_teapot