With todays technology and established interface patterns from mobile, I believe it's feasible to use the ideas of tiling window managers beyond a niche market.
Second: less-than-full-height windows can be quite useful. Being able to specify a "stack" into which, say, I place a video (or video-chat) app, various A/V controls, and possibly some monitors or other smaller windows, perhaps a shorter terminal window or three, is easily something I'd like to do.
With WindowMaker I can _arrange_ windows in a pseudo-tiled state. Unfortunately it's too easy to accidentally drag one off somewhere. Generally, though, this can be quite handy.
What I'd really like to be able to do is to specify roles for certain window locations. Say, a browser, image editor, and audio editor all occupying the same larger window space, which I can tab between.
And I think you're quite right about applicability of tiling metaphors.