The ONLY reason to mount a turntable vertically would be to save floor space. But.....if you're in such need of floor space, you'd be much better off going the digital route with all your tunes anyway.
.....so, in essence, yeah......it's nothing more than an exercise in POOR design. But, if it helps keep vinyl alive in some perverse way, then I'm not 100% against it ; Just 99%