[kjw]

What would happen if water molecules were straight?

I realize they would then be linear and nonpolar, but what changes would occur?

[jkrumh1]

For one, the boiling point would drop a lot without the intermolecular attractions to hold it together.
Water would loose most of its surface tension and ice would no longer be less dense than liquid water.  In other words ice would no longer float on water...