Too many ignorant people think it's for little kids.
I know this is not going to be a great response, BUT...
I did watch some anime on C4 about 4/5 years ago, and really did not think much of it.
And to be honest, I think some people don't like it because its NOT for kids.
If that makes sense, not sure it does to me, but this is pretty much the exact word for word opinion of my 'set in her ways' mum.
Personally I did watch some (perhaps C4's line-up was not a good example of anime) and thought it was pretty rubbish, however, people do like different things.
SE