So really I think I'm just going to drop shield for something more interesting and "active." [...] I got healing surges that are barely ever tapped. I'll let that be my defense from now on. [...] If you're not a hardcore failure mitigator by nature, shield can go.
Different strokes for different folks.
Some people prefer not to get hit at all. Some people prefer to treat their hit points / healing surges as just another resource to tap. Most people are probably somewhere in the middle.
You should pick powers that are interesting to you. If you don't like shield, don't use it. If you do like it, use it.
Oh, and discuss with your DM how he's going to rule on shield so you can make an informed decision. (To bring this slightly back on topic.)