Belts have visibly moving parts, and are supposed to look and sound somewhat like real-world conveyor belts. To that end, it makes sense that they produce sounds.
What makes a lot less sense is that pipes and wires seem to emit the exact same sounds. This seems highly inappropriate, as pipes have almost no moving parts, and wires especially have none at all.
Ideally, wires should emit no sound. Pipes could emit sound, but they'd have to be new sounds. If pipes must produce a sound, it must be a different sound than the belts sound, and preferably something that sounds like liquid flow.
(And also, if that were implemented, the pipes should only produce that sound if there were actually fluid in them. Empty pipes, like wires, should produce no sound at all.)