This. Players just keep getting stronger, faster, and more practiced.
After watching that Flying Illini v. Mizzou game that someone posted, I was shocked at how soft the defense was. There were a lot of steals, but not much of the physical, stifling defense that you see all the time in the Big Ten today.
If this 'All-Time Illini' team thing is about selecting the best players relative to their era, then some of the old-timey guys like Red Kerr should be in the discussion. But if it is about who you would take for a fantasy team to compete against each other (i.e. Red Kerr going head to head with Meyers Leonard), then the more recent players get the edge, because they're generally faster, quicker, and stronger, generally better ball-handlers, and better defenders.
Like I said, my selection is not based on their Illini career. That was a different era, different game. In todays game, Meyers would destroy him.