It's the evolution of a more athletic golfer and the science of golf technology that has evolved since then. Not to mention the evolution of golf course agronomy that is designed to give today's players the nth degree of an advantage. Those guys playing back then weren't hitting balls into fairways that were stimped quicker than most public course greens these days. So figure at least 30+ yards more of rollout today versus back then.
Yet, Nicklaus drove the occasional par4 @ 300 yards.... as did Palmer.
Not a whole lot has changed regarding strategy. And not a whole lot has changed regarding skill. But the technology of better equipment, better course setup and agronomy and the science of the golf swing in general has changed dramatically, at that level.
It makes me appreciate those guys of yore a lot more than those of today, although I'm admittedly in awe of how the guys today can hit the ball 75 yards further than me, with every club.
I respect the opinion that today's old great courses have become irrelevant, but that said - I don't ever want to see the day when these great players of today aren't hitting it further than me. Youth and athleticism is, and should be, part of the overall equation.
But it's almost like we are wrong to appreciate that aspect, as fans.