Menu bars are terrible! Visually navigating a tree structure via mousing is a nightmare, especially if the whole thing disappears or radically shifts if you mouse a few pixels off. Visually scanning huge, variable chunks of the screen is inefficient, awkward, and a burden.
Everything that you can do with those nasty, collapsible visual hierarchies can be done way more efficiently and way more accessibly via a nice search interface with fuzzy filtering and autocompletion.
When it's actually fast and unencumbered by bullshit like advertisements, something like Spotlight or the modern Windows start search is infinitely better than crap like the Windows 9x start menu.
If you've ever coached someone through navigating a graphical, hierarchical menu they've never seen before, you know how painfully slow all that mental processing actually is. Even a hunt and peck typist will be faster in most cases, as all they have to type is at most a handful of letters. Menu bars suck in the exact same way, and they ought to be either eliminated or replaced in the same way as ye olde start menu, too.
