This has already been filed (for the PIX at least) as an enhancement request, id is CSCdy26037. You can follow it on Bug Toolkit here:
http://www.cisco.com/cgi-bin/Support/Bugtool/launch_bugtool.pl
Please feel free to push your Account Manager to push this further if you really need this functionality. So far hardly anyone has asked for it and therefore it has low priority compared with other new features. The more customers that ask for something, the faster it gets in.
