yes it would..
since every function that is added that has network access is a new hole in security.
I'm sure the developers would make it as secure as they can, but network access is a security hole. That is the drawback to the whole networked systems environment.
I think that the whole collaboration tool concept is based on a flawed design. It should NOT be based on an email app.
it should be a separate app that accesses whichever resources are required for that particular users / organizations needs, with administrator defined functionality needs.
while email is a part of it, it is not the biggest part, so it shouldn't be the primary tool.
edit to add:
Seamonkey is only better as a collaboration tool because it has web browser, email, address book AND irc chat.
any collaboration tool that is focussed around communication needs a live meeting tool as a part of it.
