As I see it there are several things going on with the officiating:
1. Speed of the game is faster than 20 years ago, it's harder for mere humans to keep up.
2. With the advancement of technology, especially with the advent years ago of the super slow motion cameras, it's easier to see what actually happened, vs. what the refs can see in real time. (Which relates to point 1)
3. With more plays subject to review, the refs are having to try and decide on the fly if a penalty really happened or not, they know they will be scrutinized endlessly by coaches, and are as much trying not to make a mistake as to make a call.
4. Techniques are developing all the time, Michael Irvin made pushing off an art form, the "I was swinging my arm to get to the ball and in the process I hit the defender, not my fault I'm 210 lbs and the cornerback is 180 and fell backwards" reasoning.
Refs always made mistakes, always will. Are refs totally unbiased? Of course not, again, they're human, think if some player griped about a call too much that player might "tick off" the ref so that a close call later is called against that player's team, or not called? I just have to wonder after that uncalled Saints play, the ref was RIGHT THERE and he couldn't see it? Then the refs talked and NOBODY said they saw what was one of the most egregious missed calls I've ever seen (and I'm NOT a Saints fan)?
Officials will always make mistakes, until they can go to robot or computer officials it's never going to be perfect...