The way Apple does it is also better design than a conventional menu bar. I can see why FF and Chrome hide it by default. Most of the actions tucked away in it

The way Apple does it is also better design than a conventional menu bar. I can see why FF and Chrome hide it by default. Most of the actions tucked away in it are either used infrequently, or have common keyboard shortcuts. Turning it on in Firefox makes the chrome feel cluttered to me. By exporting the application's menu bar to an OS-provided panel that includes other OS-provided functions (clock, status indicators, wireless controls), they enforce both a strong level of consistency while allowing for reduced window clutter.