why do you think you can watch knd or billy and mandy? because they were designed for children and adults alike. it's not about disliking TTG for the humor, it's the fact it has all the "lel random" bullstuff that entices kids to make their parents keep CN on their cable.
KND and billy and mandy were produced in the early-mid-2000s. science has already proven that societal trends change as time progresses, and with it the interests of children. that's why hoolahoops and easy bake stuff was popular for kids in the 70s but isnt popular anymore.
the best way i can summarize it is 'kids these days.' its not that TTG is worse than KND or Xiaolin Showdown, but it's that you grew up watching KND and stuff like that, which was specifically made to target your generation, while TTG is made to target this generation of adolescents.
there were definitely 17 year olds back in 2006 that thought ed edd n eddy wasn't funny, but what matters is that there were kids like us during that time that thought ed edd n eddy was funny. that's why they made it, so they could get our viewership. now CN has TTG so that they can get the viewership of today's youth, and it works for them.