The initial reason I bought a hydration pack was because it was cheap! A special sale at REI Outlet.com got me a BCA MicroFlash hydration pack for $17.95 I think it was. I was looking for a small pack but not really the hydration part. So I bought this thing with the intention of removing the bladder.

I tried a hike with the bladder in place, before my planned removal, and found I was sipping water nearly constantly. Every few minutes. Much more than when I'd have to pull out a H2O bottle from inside a pack. I'd walk up a hill, breath a little harder and dry out the mouth, and found I really liked a quick sip to wet things down again. In the past I'd have said to myself, "Just had a drink - don't need another one this soon." Since you don't stop or even slow down to drink with a hydration bladder, you don't fell the urge to deny yourself and keep moving. I think I just prefer the near continuous drip feed of a hydration bladder setup over the binge/deny scenerio I used to follow.