Why not go Disc?

I was asked this by Patricles a little while back. I'm not positive if he was referring to PVP, but I decided to take a serious look. What I found was I suppose not completely startling to me, but I was amazed at how much healing I would probably lose.

I would lose the following if I went 41/20/0

+5% Spirit
Improved Death
25% of my Spirit giving me +damage and healing (buffed around 150)
10% of healing increased (before +healing applies, but it's still around +200 healing on my GHeal)
6% chance on Greater Heal, Flash Heal, or Binding Heal to have a free next Greater Heal, Flash Heal, and Binding Heal (this is how I base my regen periods for boss fights, and is probably the most critical of all these points.)
Lightwell
An additional 12% of my +healing added to Greater Heal, and an additional 6% added to Flash Heal.

That's a lot of healing. My heals would probably be 80% of the size that they are now without all of that above. What would I gain? Mostly stuff for PVP and lolsmite. While I enjoy a good lolsmite build, right now I'm focused on my healing in Karazhan. Back in Molten Core, it wasn't a big deal for 1/40th of the raid to be an offspec. Now, being 10% or 6% of a group makes me feel far more important and essential. Sorry disc, I knew thee once, but I love my PVE spec.