I agree with most of the things said here...except for "They're fine as they are" BS. Claymores do need to be destructible. They're not like AT Mines or C4 with very specific detonator systems. Almost anything can set them off, and it should be that way in BF2. I like that teammates can't set them off, because that makes them useless, but making them nigh invulnerable and allowing them to remain long after death DOES make them practically a guaranteed kill. if they were destructible, at least people might have to THINK about where they hide them, instead of just tossing it with full knowledge that someone would INEVITABLY get around to it.
I think AT mines should still be destructable from high explosives, but they should be buried of camoflauged when they're planted, so that they'd be almost impossible for enemies to notice.
As for C4, well, they're not set off by just anything, so I'm not sure how to handle those. I've never really had much of a problem with them, because at least THEY have to be watched or payed attention to to snag kills, rather than just planted somewhere so you can just walk away. I'm fine with C4, because if they were easily disabled in ADDITION to needing intentional detonation, they'd be kind of a pain in the ass. Maybe if when an engineer or special forces guy tried to disable it, there'd be a percent chance it'd go off in their face. That'd be fun to watch.