Well, my love for many of the Eastern European cartoons and lack of it for the majority of the American ones has more to do with the characters. In many Eastern European films (not in this one, which I find unpleasant) the characters feel like charming, warm, imperfect, amusing, thinking and feeling creatures with a complex set of qualities that makes them a great companion. As a child I would love to have a creature like this for a friend. American characters always look like they are trying too hard to be entertaining, and I would prefer to keep away from somebody like that. They are egocentric, demanding, hyperactive, loud, over the top, in your face caricatures who might occasionally be funny but nobody in their right mind would want to spend any time with such a nuisance in real life. They look like they would be pulling your hair and screaming in your face and forcing you to do ridiculous things. So whether it’s the Incredibles or Duffy Duck, or Family Guy, I often watch them with mixed feelings of amusement and certain distaste, as one would watch a circus clown, kind of: do your tricks, some of them are funny, but please don’t get too close. So my point is that of course all is a matter of taste, but unlike what somebody said about having a sense that “Eastern European cartoons were made with the expectation that no one was watching”, they WERE made for an audience, but a different audience.
This is indeed a defining trait of most Soviet cartoon heroes. Some popular examples (subtitled): Cheburashka (films 1, 2, 3, 4), The Kitten Named Woof (films 1, 2, 5), Buttermilk Village (films 1, 2). Characters are more likely to be vulnerable and kind than stylish and showy. This began to change in the 1980s with films such as Tatarskiy's "The Koloboks Investigate" and Cherkasskiy's "Treasure Island" (part 1, part 2), which were more circus-like. Tatarskiy's first choice of profession was actually to work in the circus.
There is another difference that is more universal. To make it clear, I will begin by quoting Paul Wells' classification of the cartoon body from his 1998 book Understanding Animation, p.188-9:
-The body is malleable - it may be stretched over long distances, be compressed or extended, take the shape of another form, fit into incompatible spaces, etc.
-The body is fragmentary - it can be broken into parts, reassembled and conjoined with other objects and materials.
The body is a contextual space - it can be a physical environment in itself, which may be entered into and used as if it were ostensibly hollow.
-The body is a mechanism - it may be represented as if it were a machine [in either the literal or Deleuzian sense].
-The body has impossible abilities (i.e., it can fly, lift heavy objects, experience violence without pain, etc.).
-The body directly expresses explicit emotions (i.e. it fragments in surprise, contorts in terror, etc.)
-Bodies of humans/animals/creatures which are apparently incompatible are rendered equable in size, strength, ability etc.
-Bodies may re-determine the physical orthodoxies of gender and species.
These apply to much American animation. None of these traits except for the last two are typical of Soviet animation. (Tatarskiy's 1981 cartoon "Plasticine Crow" was revolutionary precisely for the reason that it did have the other traits)
I remember not liking “Looney Tunes” very much when I first experienced it as a kid (I started out watching only Russian cartoons) for basically the reason that the characters were not “real” to me; I could not believe in them. They broke the laws of physics, got sawed in half, even died, and were back the next frame as if nothing had happened. No consequences, no progression, the next scene always a reset button.
This never happens in Soviet animation, no matter how modern the art direction is. If someone falls, they get hurt. If someone dies, that’s it. There are consequences to actions. Even the popular “Nu, pogodi!” series is like this, which is its main difference from “Tom and Jerry”, to which it is often compared.
As a bit of an aside... maybe this explains (or is explained by) the never-ending American optimism for new beginnings. “The past is past”. Elect a new president and everything will be fixed… and after he does an awful job, believe the same thing about the next one. “I can stop any time I want to”, etc.