One for, one against, which is where I was when I began. I wish a developer would chime in. :P
I note under Web, if you're free and moving through a webbed area, you only roll once to see if you're trapped, not every square, so I do see your point in some other spells already.
As you point out, the movement penalty is essentially an auto-fail. If you have a 50% chance of making the save, moving through a single area (20 feet) is a 6.25% chance of making it through without penalty, which seems ridiculous, and the monsters lined up don't have reflex saves even high enough for those odds.