Electrical - converting 3-way to single pole for multiple fixtures
Three way switches offer a convenience that is sometimes not appreciated until you eliminate them and then are living without them.

One thing to consider if you are trying to split these four light fixtures into two in order to have times when your whole kitchen is not blaring in full light is to consider a different approach. You could replace these two 3-way switches with 3-way type dimmer switches. 

This could give you want you want, reduced lighting, whilst being able to use the existing in place wiring. Depending upon device selection you could also get the ability to control the lights remotely.