Just look at the current landscape of animation. Only including American animation that started after the turn of the new decade (2010's), and are still running, we have Adventure Time, Regular Show, Friendship is Magic, Amazing World of Gumball, Gravity Falls, Wander over Yonder, Steven Universe, Clarence, Over the Garden Wall, and now, Star vs. the Forces of Evil. That’s ten acclaimed cartoons made in the last five years alone, and that's just the top of the barrel.
Say what you want about these cartoons, but admit it; it’s a lot better than the dark landscape of animation that it was back in 2006-09, with only like three or four shows worth watching, with the rest being sub-par to bad for anyone above the age of ten.
Also, notice how no show I mentioned came from Nick. Sure, there was Korra, but it was canned recently, and unfortunately doesn't qualify in the "still running" category. Apparently, they're still stuck in the dark era of animation, even though Cartoon Network and Disney have moved forward in recent years.
Do you think these cartoons are on par, or better than those of the 90's? Just the fact that they appeal to teenagers and adults in addition to children, without the rose-tinted nostalgia filter in the way, strengthens this point further. Also, people who grew up with cartoons in that era are now working in the industry, therefore, they have that influence in their works.