I completely understand. I feel the same way about Suzanne Brockmann! (Although now her out of print stuff is being put back into print, finally.)

Part of the problem here is that publishers only have so many slots -- and unless an author is Nora Roberts, we just can't, most of the time, justify using a mass market paperback slot for a reprint. I am not saying this is the only reason -- but it's definitely one of them.