I'm not so sure the umps are that much different than in the past. There's a couple guys, Angel Hernandez comes to mind, who seem to go out of their way to find the spotlight but my thinking is that there's so much more TV coverage that umpire confrontations are noticed more often nowdays.
I seem to remember umpires yelling right back at managers like Billy Martin and Earl Weaver.
And what was the guys name who wrote The Umpire Strikes Back? He was no stranger to confrontation.
There was a Cardinals game in '79 or '80 and Ted Simmons was at bat. He took a couple called strikes and was barking at the umpire but not really causing a big scene. Same at bat, he hits a home run, rounds the bases, steps on home plate and, without a word, tips his cap (helmet) to the umpire and the ump threw him out on the spot. Now that's confrontational.