These are both very good points, and also why I don't put much stock in retro-snobbery.
1. Most of the people who romanticize, if not outright deify, the cartoons from the so-called "good ol' days" (i.e., the era they grew up in) tend to forget or just choose to ignore the less-than-stellar cartoons from those same eras. But the truth is that suck has always been with us, and it will always be with us. Retro-snobs tend to gloss over the fact that for every Tom & Jerry, there's a Herman & Katnip. For every Daffy Duck, there's a Buzzy the Crow. For every Scooby-Doo, there's a Goober and the Ghost Chasers. For every Ed, Edd 'n' Eddy, there's a Mike, Lu & Og. For every Tiny Toon Adventures, there's a Histeria! It's been said before, but nostalgia blinds us to the fact that suck is eternal.
2. The other valid point raised in Dr. Pepper's post is that as we get older, our tastes in shows tend to change, particularly when it comes to kids' cartoons. Most of the people who make pat assessments like "All of today's cartoons suck!" are simply too old to enjoy them. Going back to point #1, I, like most us, watched plenty of crappy cartoons as a kid, and since I was a kid at the time, I loved every moment of them. Take a good chunk of the shows that you loved as a kid, then try to watch them now, and see how many of them hold up. I thought The Three Robonic Stooges, The Shirt Tales and The Super Globetrotters were 'the stuff' as a child, but I can't say these shows carry the same weight for me at 41.
To sum up: I can't take the act of uniformly trashing every cartoon made after a certain year or era seriously, and the above reasons are why.