I can see that it could potentially cause problems compiling it when not expected. For me though - that's one of the things I like about PL/SQL Developer.
If I have a package in one test database that needs to be in another test database, I just view it in one database, switch the connection and compile. Being read only makes sure that I don't accidently change it.
So...if this is changed, maybe it could be a preference.
Thanks,
Mike