Why does it seem all new faucets are using braided hose instead of stainless steel?
Durability - I have often seen the stainless/chrome plated hose breaking up after a few years... this is where the hose splits along the seam of the hose... This will not happen with the braided hose due to the fact that you have a netted sheath.
Also. the braided pattern is more flexible than its counterpart. 

Cost -  This hose is substantially cheaper than the corrugated style hose.

Ease of manufacturing and assembly:  this hose can be crimped during assembly, the alternative is to use more complex and expensive screw clamps to assemble the unit. 

You will probably also find the regular stainless braided hose like this: