Lost in disc space
Certainly, in the scheme of things, it isn't that important. But because a casual decision on a programmer's part can cause countless hours of lost productive or leisure time, it does matter.

DVD menus suck. And they're getting worse.

What is the purpose of the menu on a DVD? Is it to help me find the features I want, or is it to show off the programmer's ability to animate menu transitions? On the Harry Potter DVD, for example, the second disk is almost all menu. It's a menu-based game of sorts, a puzzle that must be navigated in the right order in order to get the prize: Seven short deleted scenes, none of which will surprise anyone who's read the book. (Instructions to bypass the noise and go straight to the signal are widely available: I found them first at Ain't It Cool News, where Alexandra duPont calls the puzzle an "Easter egg" minefield.)

(As long as I'm on the subject of the Potter DVD, why didn't it contain these photos?)

I detest commercials / trailers / promotional materials that you have to watch before the menu comes up. I've already bought the disc, people. And I don't scan the paper on Friday nights thinking, "Gosh, it's been ages since I've gone to a Warner Brothers movie!" Instead of making me sit through a pep rally, just put your logo on the main menu page as a "bug" in the corner. Goodness knows you know how to do that.

There's no point to a "languages" submenu if you only have one language on the disc.

This article suggests some improvements the industry could make.