Yes, the 90s and early 00s cartoons have more creativity than most of today's cartoons. They made cartoons back then for kids AND adults. Today's cartoons like Uncle Grandpa and Teen Titans Go!, modern Spongebob episodes, Sanjay and Craig etc just depends on random and gross humor. They don't have good plots, and complex and likable characters.
The only cartoons I like now are: Regular Show, Adventure Time, Wander Over Yander, and Gravity Falls.