Well me too but if i could just jump off of stuff if be skipping the stairs a lot more often. I agree with the other person, seems logical to me that for a prey animal they'd be careful about changing their threat landscape too fast. Once you let gravity take over there's no telling where you'll land. You could roll right into a ditch or a cats paws. And maybe they actually do jump sometimes, but only when there's certainly no threat nearby, which would involve no human observers, or maybe seeing other mice where they plan to land.

And then there's the actual vision. Are mice known for being able to see long distance? One could posit, if not then most jumps would be leaps of faith into vague amorphous blobs, full of potential danger and impossible to triangulate or assess.

I tend to wear jeans with skinny legs that don't seem conducive to taking across-the-stairs (I'm thinking 3 to 5 meters in the horizontal direction) jumps.

Why do I wear impractical clothing? I never even thought of it as impractical.

Cats live warm--what is a perfect thermal balance for them (where their body needs not expend any effort for heating or cooling) is unpleasantly warm for a human (who will be sweating.) Typical water will be chilling for a cat. Going swimming in most environments will pose a hypothermia risk at times and thus fearing it is a logical evolutionary result.