Believe it or not, it takes a great deal of work and intuitive knowledge to develop a unique style of abstraction. So many people settle for a slight variation of what has gone before. Matisse may have been able to be more unique as he was one of the first to delve into abstraction. So it is doubly hard for us following him to be more unique.
I don't know, it might take even more work and intuitiveness to appreciate abstract work!
I'm partially kidding here, I for one think that the art world is absolutely enriched and enhanced by the presence of abstract work. It makes it an altogether more interesting and free place. Sad would be the day when all art had to be kept within tight borders of any kind.
But as always, even though I like abstract work, I sometimes wonder how the term "greatness" gets attached to some of these folk - Matisse for instance. Not for his line work or use of color, I don't think. And that the art world thinks him great seems more of an offhand compliment. Anyhow, I do actually like his stuff well enough.
'Course, I am always the first to admit that the standards that really determine the greatness of art are also the most elusive to pin down. The abstract ones.
Seriesly though, while all artists build on what others did before, if it was any good, everyone's work will automatically be original, as long as they aren't consciously copying the style of someone else. I don't think the possession of skill should disqualify one from producing "good art."