MAME's orientations are wrong for some games? I never noticed any games flipped on their sides or anything like that.
They don't have to be, but they can be incorrectly listed as horizontal/vertical (I don't know why). See 'mame -wrongorientation' - I don't actually understand what this means exactly...I haven't been through the games to check.
Seems to me that orientation and resolution should be independent. Can't you have a 240x224 game that is vertical?
Well yes

But lets make an example: I use a horizontal screen, so lets l might want to display purely horizontal games, or more realistically games which will display well on a horizontal screen (as a rule games whose pixel width is greater than height) . So based on your 240x224 vertical example above, this would be filtered out of my horizontal games list - BUT, it would display fine (arguable perhaps on how much of a purist you are) on a horizontal screen. So, for this example this game would be best listed (for me) as horizontal, so it is not filtered out.
That alone is the reason I added this option - basically to maximise hits when filtering on orientation. Granted I might be alone in my thinking here, but you can turn it off as I say
