So: bitcoind doesn't ask for confirmation before sending fees with a transaction because it is was much easier to implement that way, and for most uses of bitcoind paying an occasional transaction fee isn't a problem.
If you'd like to help fix it, patches are welcome. I think a new setting that says "don't pay more than N bitcoins for any transaction without asking me" and a new argument to the send routines to say either "I'm willing to pay up to X bitcoins for this transaction" or "I want to pay X bitcoins in transaction fees with this transaction" is a good idea.
I think there are more simple and correct solution: block with giving error message transactions, which required more fee than paytxfee option. And setting individual fee for each transaction leave for the future.
Or in other words, just say "No" by default on the issue of additional pay for the size.
I think a new setting that says "don't pay more than N bitcoins for any transaction without asking me" - not really needed option in this case.
About the patch: I know C, not C++ and not so well know bitcoin code. So I can make mistake due to which someone will lose a significant amount of money. After all, I was just lucky that I had lost 0.13, but not 13 or 130 BTC...
Not that I really offended you, but the existing behavior bitcoind really dangerous for those who send large amounts from CLI.
Sorry for my bad english, i use google translate...