If you look at the old film from even those made for TV match play events in late 50s, early 60s, you will notice many players did not have a modern pendulum swing.
If you ever happen to play really slow greens, your pendulum swing might not work as well.
Having to take the putter back too far, much farther than normal, on the shorter putts is a bit troublesome.
If Tiger always putted on 9 stimps, he would eventually be the best putter again, whining all the way.
I think the change, adjusting to the change in speeds, doesn't suit many of the pros.