Why Are the Simplest Things Impossible To Do?

As the title says, why are the simplest things you want to do in this game, especially in Build mode, impossible or hard to do?

For example, building a water fountain up against a house is fine BUT if it comes up against walls in a basement, FORGET IT.
GAME: "Sorry, you can't do that."
PLAYERS: Why?
GAME: "I don't know, you just can't."

Want to add a water fountain inside a luxury house, under a ceiling?
GAME: "Sorry, you can't do that."
PLAYERS: Why?
GAME: "I don't know, you just can't."

Want to put a water fountain in a basement?
GAME: "Sorry, you can't do that."
PLAYERS: Why?
GAME: "I don't know, you just can't."

Last night I started replicating a lovely house with a water pond underneath a FLOATING staircase on the 64x64 lot in Brindleton Bay but as soon as went to play the "floating" staircase above the water fountain, a message said "Modular staircases cannot be placed in water." HELLO, it's a FLOATING staircase. It's not even in water. It hovers above it.