Let me remind you - there are different kind of applications. Ones that are just small windows, fullscreen applications, many different needed sizes. You can't assume everyone should use the same window size for every application, can you? You can't assume EVERY window is fullscreen.
That's because he probably wants it to be compatible with all kinds of computers, even the minority. Why do you have to be so mad at Elysia? It was just a suggestion.