I'm inclined to agree, however, sometimes those blunders can be helpful. Not so long ago, Obama was talking about some sort of military deployment into Syria. For such things, it's generally considered that us Brits will go along with whatever the yanks want, so we'd have had to go too (just like Iraq, which wasn't even legal).
Cameron put forth a motion, which needed a vote. However, he did it with such a short time scale (because he's "eager to help"), that he was defeated and thus, the UK could not participate in the Syria plans.
We can argue about whether the US/UK should or should have not gone into Syria at that time. Had it happened though, it would have been another illegal war with undefined objectives, and a huge expense for the UK (which was very contra the 'austerity' of the time). As such, keeping out of it seems like a wise thing to have done. Of course, it wasn't followed with a proper, UN based plan or anything which is arguably why Syria is in the shit state it is now, but that's another problem.
As for this one though - it's pretty obvious he's been leant on by the Americans again. If it gets through, then the NSA gets a whole new avenue of data collection, and if it doesn't, then the NSA/Obama/etc don't lose any political capital in the attempt. I suspect the latter as it's unworkable. For example, I'll make sure my servers all talk gibberish to each other constantly, should any laws against encryption be passed. Who's to know if it's data or cyphertext?