I would not say that his influence is not heard too often. I'd say, you hear his influence very often, but do not really notice it, if you don't pay attention to todays drumming.
Most of what Keith did back then was - just like Ringo - new territory. He started e.g. fills on 2 or 3 instead of 1, added melodical patterns, interpreted the vocals on drums, added triplets to the standard-repertoire of drummers. Most of what he did back then is part of many of todays drummers arsenal, yet nobody uses these tools as concentrated as Keith did back then.
Because Keith came up with those new and rather jazzy approaches to rock-music first, and because nobody else played it back then (of course), he really stood out in his era. Today, all those ideas he came up with, double-bassdrum patterns, tom rolls, the cymbal accents, the triplets, the "growl" of his floor-toms, mimicing symphonical timpani, all that can be heard when you listen to e.g. Peart, Portnoy, Tim Alexander, many Metal-drummers and so forth. But they only use from Keith "repertoire" those specific parts that fits the music that they play - which is of course different to the stuff The Who made.
