I fail to see where Google has a problem.
Gnome is the default DE of the three main distros, Ubuntu, Suse and RH/Fedora, so - and that's what they did - it's quite logical to do the port on Gnome.
Now Chrome is open source, so if anybody want to port Chrome to QT/KDE, well, they can.
As to why Google wants to port Chrome to Linux, well, they need to show goodwill to the open source community to beef up the Android Market.
And finally, I think we'll see the Gnome/KDE duality for a long, long time, simply because some people prefer C and others C++ and we're talking about free software.