Why does Ubuntu 14.04 change macbook pro 11,5 mbr to hybird?

Disk is scrubbed. EFI and MBR is created. NTFS primary partition is build.
Windows is loaded EFI
Ubuntu is loaded live mode EFI.
When using Ubiquity to install Ubuntu and we create / and swap partitions.
As soon Ubiquity commits the partition changes ... it modifies the MBR to be hybrid?
Why Why Why?