Of course it is better. A pop up can be in some code path that only seldom is executed. For someone loading the code, no warnings means that everything is ok. Suppose they install it on a server side image thinking that everything is ok. Then sometime after that, the image stops working because the headless mode can't allow to see the popup that is waiting for someone to press a button. Again, the GUI is  good sometimes, but sometimes is better to fail earlier. If on loading it doesn't load because of some missing method, the user can see right there that something is wrong with the package is trying to use.
A robust server will have proper error-handling. I put a check for #maIsHeadless in my error-handler for Warnings so that they'll never halt when headless, but output a line to the log file. With that out of the way, that leaves, "the GUI is good." :) - Chris