“Cartoons” have an English interpretation for being narratively simple. Whether they’re 3-4 panel comic strips or political speech or 30-minute kids shows, they tend to be fundamentally bite-sized morsels of media and do not traditionally evoke notions of grand storytelling or significant narrative merit.
There is no shortage of anime series and films that I’d classify as cartoons. Cartoons are fine and respectable entertainment, but they are only a small subset of all animated media.
Fans of the anime art form are justified in bristling at someone who calls all anime “cartoons”, or animated media from any other country for that matter. Tokyo Godfathers, The Tale of Princess Kaguya and Mind Game are all dense, complex films, which pushes them outside the bounds of what most people categorize as cartoons. Yuri Norstein, Hayao Miyazaki and Jan Švankmajer make animated films, not cartoons.