Well to each his own I guess. I honestly don't see why some people are not impressed by these. Its like not being impressed when someone breaks the land speed record because they used a rocket car instead of running.
I like TASs because they push the boundaries of what it is possible to do in a game. And its not as though they are easy to do either. They take a lot of knowledge, patience, and often very creative thinking. To me it is a challenge different, but no less impressive, than unassisted runs.
More information on TASs for the newbies: TAS Why and How Wikipedia entry on TASs
Well, I would think that the fascination of breaking of a land speed record in a rocket powered car has whole lot more to do with fascination with what can go wrong with breaking of a land speed record in a rocket powered car than it does with the actual fascination of the process of breaking it.

If there was no human life risk, then there would be very little interest.
A TAS run is nothing more than a run through a broken game. It may take some skill, but running through a broken game is lame. Who cares if he made it to the end with no stars? He broke the friggin game, so stars mean nothing anyway.