Tricky topic. Still, this is a bit of an apples to oranges comparison.
Thirty years ago, there was no break box, the one ball was on the spot, and the wing ball was dead, so players had a better chance to control the cue ball off of the break. As you note, they liked to squat the cue ball near the center of the table. They would love to do the same today, but ....
Today, in WNT play, which is currently the highest level of 9ball competition in the game, there is a narrow break box, the nine is on the spot, and the wing ball is no longer dead. To their credit, today's pro players have devised a cut break that enables them to make the one in the side with relative consistency, but the cut break comes with far less cue ball control. Today, the break that is in vogue in WNT play brings the cue ball to the rail and back through the rack area, so it is much harder to end up with a shot on the two ball after a successful break.
Hence, you are correct. Yesterday's players liked to squat the cue ball, but chiefly because they could under the old break rules. Today's pros, with few exceptions, have determined that they must cut break to ensure that they don't break dry, and in doing so, have ended up with far less cue ball control than their counterparts of yesteryear.