Awesom_o's question is very much to the point, it seems to me. It all depends on whether the sort of music you want to play would benefit by practising them. Last year a friend teased me that I could not play smooth scales in the usual up and down way so I practised for a few weeks until I could. However, bits of my improvisation started sounding like Czerny studies - no rhythm, no life - so I went back to my old, rough, group based way of playing them, and all keyboard partitions.
So for me, no, not at all necessary, at least not in the usual way, but for others of more traditional bent they might be just the job. I use them of course, they are just arbitrary keyboard patterns after all, but as Dima implies, I have to use them, and all formations, in different ways every day to provide musical interest, else I feel I might as well be playing a typewriter. Life is too short for that.