What you call for is in essence - mitigation, yes it's fine to mitigate a "vulnerability". But shouldn't we be concentrating on finding and fixing the root cause instead of trying to mitigate the problem in (hundrets) of third-party applications ?
If the application is what exposes the URI handling routine to untrusted code from the internet, then it's the application's job to make sure that code is trusted before exposing system components to it's commands, no?
In this case how is acrobat reader any different than telnetd? If telnetd exposes system functions to untrusted users (no password required) who is supposed to enforce security? In the case of acrobat reader, it's acrobat exposing the system to untrusted sources and it should be that application that is responsible for mitigation of attacks via those exposed interfaces.
Geo.