Surely there are two kinds of 'oddball' formats. On the one hand there are those that provide a more pleasing aspect ratio within the normal range of rectangles (whole plate, 5x7 inch, 13x18cm. etc), and those that go way outside this (6x17cm, 6x24cm, 4x10 inch, etc.)

The former are easy to use by anyone who likes a better shape within the usual range of shapes (not the squat, ugly 4x5/8x10 for example, OK for portraits but of limited use for anything else), while the latter appeal only to a few with a particular type of vision. The 'particular type of vision' is not one whit inferior: just rarer and harder to try. And, in all fairness, sometimes favoured by those who can't compose a decent picture in any format, and therefore try the bizarre in desperation.