Maiming the main character

So why is there such a trend with the books I read for the authors to maim the main character?

I've come late to the Walking Dead comic series (thanks michelle), and I'm really enjoying it up until -SPOILER ALERT- our main hero gets his hand chopped off.

Kind of a pain to get invested in a character and then have to see them go through that.

True, the point is probably to have them suffer and allow us to feel further pity for them... But come on, that is something that I cannot identify with.  (sure could I identify with walking zombies?)

Also this is a permanent change to the character and how he'll adapt to life... I can feel that frustration.

I've almost stopped reading for that reason alone.

But it's happened so often in sorties and it is so annoying.

Wheel of time - rand gets his hand chopped off (I have yet to get back into that series, but that is another story)

Star wars - all sorts of people losing limbs there

Dune - Paul is blinded

Robocop - enough said, but this was the point of the whole movie

Evil Dead - and this was only so he could put a chainsaw in it's place, so it's forgivable.

Lost - Boone had a leg amputated before he dies... So at least we don't have to worry about our character living with the maiming.

The Dark Tower - Roland loses much of his main shooting hand.

And I'm sure there's more... But I think it's highly frustrating for a reader.

Especially as I'm not even half way through The Walking Dead, how is Rick going to be as an effective zombie killer...