or something non liquid - plastic balls, foam pit etc.

After flying on parachutes it's pretty hard to land on a pre-determined place, and the smaller the place the higher chance of missing it. Falcon-9 first stages have more control authority, and even they sometime miss the landing zone if the wind is particularly unfavorable; but they are unmanned and the stakes are lower, in worst case they just won't land softly. Can't have that with manned capsules, so has to have parachutes, so is subjected to winds...

Interesting point. I fly kitesurf kites, so I know a fair bit about piloting a bit of cloth above my head. I'd guess a parachute / kite would be a fun way to land the capsule.

Maybe, and capsule designers considered it. I guess reliability issues dictated dead simple solutions, which lack in landing precision but excel in ensuring survivability?