/jp/ - Otaku Culture

I have a question.

Could someone please explain to me why so many shounen/rom/SOL anime series often feature little pets or animals that the core cast unquestioningly and unanimously accepts as part of the group? There's always a little pig, or a little demon creature, or a little puppy (varies by genre), that everyone talks to like it's a human being, and its opinions and feelings are seriously considered. They are often asked to agree with a certain opinion or statement when one of the characters offers one, and the little piggy or puppy will snort or bark in reply, sporting facial expressions, etc. They are sometimes even given screentime during important dramatic moments and in a few cases even have a direct effect on the plot.
What baffles me more is that these little animals are (as far as my experience goes) always voiced by seiyuu, who often have to make quasi-barking or whatever-have-you sounds for them. I mean, I get it, it's not live-action, but still, aren't there tons of stock sounds for this stuff?

I know that even Western cartoons, films and shows sometimes feature animals with similar roles, but not with the same zealously followed cliches and similarities that are shared by the anime counterparts. Or at least they don't stick out as much for some reason.

It's not really that it's cringeworthy or that I hate animals, it's just that the way they are portrayed is so bizzare and unrealistic that it takes me out of immersion somewhat. I mean, do they really have to go out of their way to add these creatures everywhere they possibly can? Does their presence really affect sales to teenage boys and girls that much?

Please don't tell me it's some kind of traditional culture thing that is now expressed in a sublimated form in a post-war climate.