@rahm_sahriv and @Trillian Japanese animation was inspired by early Western animation (such as early Disney animation like Steam Boat Willy), which is also characterized by large eyes. Large eyes are more expressive and more appealing to audiences; they are probably the most expressive parts of the human face. Therefore it’s quite logical to make a cartoon character have large eyes. If you compare the faces of Astro Boy, one of the first Japanese anime, and early drawings of Mickey Mouse you won’t see that many differences, even considering that one is a mouse.
The gradual change from this style of eyes to more recent styles is probably just based on what the public likes. Since the anime style tends to be very similar, the most important differentiating aspects of each character are going to be the eyes and hair, hence the huge, expressive eyes and crazy hair of unnatural colors. You’ll also find that some characters, like men and villain characters, have more normal-looking eyes that’ aren’t all that different from American comics.
This video discusses whether anime characters are “supposed” to be Asian or Caucasian. It discusses eyes, face shape, etc. It’s rather interesting.
As for the original question, I’m going to assume by “people” you mean non-Asian people, because anime is watched by the vast majority of people in Japan (as well as many other Asian countries) regardless of age and interests. Anime is very different from anything else found in the Western world, therefore it’s very intriguing to many Western people. Anime in Japan is not considered juvenile unless the theme of the show is specifically targeted to small children. With the amount of violent and sexual anime out there I would be very afraid if it was only watched by children. This of course is not true in the West, where comics and cartoons are kid’s stuff, and adults who enjoy them are considered strange. There are many types of anime, including action, mystery, comedy, romance, in addition to the anime we know best in the West (Sailor Moon and Dragonball Z, specifically). Most of the people who are adamantly opposed to anime are simply not very educated about it, because if they saw some of the amazing animated series and films out there (such as Miyazaki’s Spirited Away) they probably wouldn’t think it was so stupid.
Needless to say, the crazed fans of anime are enough to make some people hate it, I know. Having just returned from an anime convention in Boston with over 17,000 other people, I can attest to it myself. There are those who get so into anime that they think it’s the best thing on the earth and develop an obsession with anime and what they think Japan is like. These “otaku” are usually socially awkward people to begin with, and the interest in anime can make them seem even more strange. One of my first anime convention experiences was being stuck in line next to a very large, boisterous girl who kept squealing at the top of her lungs and talking about how she bought a drawing of some Naruto character laying naked on a beach. However one cannot judge anime by its fans, since there is a lot of fantastic anime and manga out there.
I could probably write a whole term paper about this, but I’ll stop here. I hope this gives you a little insight about the subject. As you can tell, I enjoy anime and Japanese cultuer quite a bit, but I pride myself on not contributing to the “weird, fat, smelly, obnoxious fan-girl/boy” stereotype of anime fans.