Incompetence and lack of vision
[Disclaimer: I'm a VMware partner.]
Let's continue the analogy, shall we?
1) Very few drivers want to build their own car.
2) The cars built upon the XenSource engine do not perform better than the cars built by VMware, as shown by recent benchmarks (from both camps)
XenSource playing the open source game is a farce: all their add-ons on top of Xen are proprietary.
In contrast, VMware's ESX entire source code is available via the VMware Community Source Program to anybody who is serious about partnering (you just have to explain what you want to implement and swear that you will not make the source code public).
Many partners (including myself) are making BIG money with VMware virtualization. That is the very reason Intel and Cisco have bought slices of VMware.
Of course, this is a competitive place: some partners win, some partners lose. The winners are happy and stay with VMware. The losers whine, and they talk to other losers like Mr Crosby.
Bashing the winners' cash cow (VMware) is not a good way to befriend the winners.
I think Mr Crosby is just trying to justify its inability to make money out of the Xen code base. Nobody wants XenSource because nobody needs XenSource. With the advent of hardware-assisted virtualization, paravirtualization is dead. And just in case you haven't noticed, the once overhyped Xen is no longer the cool kid on the block in the open source world: KVM is.