That could be seen as a disadvantage also. I don't subscribe to that world view, but it's a legitimate concern.
I'm not sure I do either. It does make quite a lot of sense, but then you get the "how do new things get adopted" problem. I would probably weigh much more heavily to it if I was a manager at a large company.
That is a really interesting reason to go with the popular open source solution. I guess I don't always follow that advice, but I wonder why I didn't think of it as a security decision.