But the open command doesn't allow you to pass the environment, and Apple seems hellbent on breaking every workaround they've implemented over the years (e.g. ~/.MacOSX/environment.plist).

So, doing Foo.app/Contents/MacOS/Foo is often the only way to launch a GUI app while inheriting the full environment that you have on the command line.

I often have to do this to launch various developer tools, and have them be able to inherent important environment variables, e.g. database credentials or secrets,