Consider the 100m dash: not counting drugs, everyone who competes comes from the same place as everyone else. They're human, they worked hard, they're fast.
With the paralympics you've got a huge range of variety in the disabilities of particpants. Does one guy with three extra inches in his left leg have a better chance than the guy without? Is it fair to have them competing?
I'm reminded of Oscar Pistorius, a South African runner who had both his legs cut off when he was 11 months old. He has had specially-crafted carbon-fibre blades created that allow him to run faster than many full-bodied people. This poor guy's got nowhere to compete 'cause he's so much faster than other paralympians he challenges the regular runners. The problem, as described in that article, is that there's no agreement about whether his disability counts against him (half his legs missing) or for him (specially crafted mechanical replacements).
And the paralympics are an entire olympics worth of people with varying disabilities competing against each other? How on earth is that even remotely fair?
So I don't watch it. Kudos to them for working hard and having fun, but I can't sink my teeth into a competition with such variation in competitors.