Honestly now? Aqua was a rather late change, and OS X was technically already released on the market before the Aqua UI existed (for those of us who remember MacOS X Server 1.0, which was very much like Rhapsody DR2, which was essentially NeXTSTEP skinned to look like MacOS 9). Anyways before even that Steven spent a lot of effort cleaning out the Apple closets of a lot of the people from the previous 'administrations' and installing and promoting people he brought over from NeXT.