i should have been more specific. i don't like the idea (at all) of
breaking traceroute -g either. i guess in a more general sense i
should ask "just how dangerous *is* having backbone-wide/internet-wide
loose source routing enabled?".
As Curtis explained, "not very".
Worst case, those folks feeling victimized can (and do!) simply shut
it off.
This is a very different case from that of SYN flooding, where the
victims are powerless to stop it.
Please don't take our LSRR away from us, it is very useful.
Campaigning to remove something just because you suspect it might be
bad is really not nice -- it will result in random clueless people
believeing you when perchance they should not 
--jhawk