"True. In those situations where you want to switch your proxy 300 times per second, this is very important! ;)"
Well you never know... No, from a performance point of view you are quite right. However I have been in the situation where I've been on machines which are constantly running out of process ids and every little helps (eg: echo *). Admittedly I don't see switching your proxy on and off would be a particularly high priority in such a situation!
"Trading some performance for modularity and maintainability is usually a pretty good idea."
You've lost me slightly there, I would have thought having one .cshrc (or .bashrc?) would be more maintainable than a bin directory full of separate files. I guess we all have our preferred ways of working!