Not every style has to be considered a Martial Art, some are just fighting styles/systems pure and simple, they had nothing to do with the MAs at all.
Really, is martial "art" even the most accurate english rendering? Or was the term simply more appealing to western society?
Most, if not of the "arts" that were initially brought to the west would have been rendered better as "martial way," rather than art, as 'do' does not translate as 'art.' Even the word that translates better as 'art' is really more indicative of skill.
It is the 'do' that implies all of the spiritual and personal development aspects that we associate with TMA, not 'art.'
The problem is that when we in the west hear the word 'art', we associate it with fine arts. Art as a term in the west has connotations that go well beyond, and indeed, often don't even touch on
skill. Very little of what I see promoted as "art" these days requires any skill at all, provided you can spout off enough bull and have the right political outlook and social connections. Oh, and suckers with money helps too.
But we do have the connotation of 'art' in the west as pertaining to skill. We say things like, 'well there's an art to doing it correctly' or 'that athlete's performance is beyond just skillful, that is art!' Art in the sense that Captain Sullenberger's ability to handle that jet was 'artful' or a Nascar driver's ability to thread a vehicle the size of a full sized modern car through a field of other full sized cars at over a hundred and fifty miles an hour is an art.
In the sense of how an 'art' or jutsu differs from a 'way' or a do, then fighting systems without all of the cultural trappings are most definitely martial arts... if by 'art' you mean skill.
Daniel