I've noticed the need for combining Sencha Touch and Ext JS a while back but just didn't say anything as I've read in several places of others asking the same thing, even at the conferences, and Sencha always seemed to have no intention of merging them.
Windows 8 is now reportedly sharing technology that powers their smartphones and based on the web-stack just as Linux Gnome is trying to replace several core components based puely on the web-stack, no to mention the hybrid thin apps that are becoming dominate from languages and frameworks like Qt and ActionScript as well as server frameworks like Drupal designed to handle thin-app creation.
Getting to the point, It's unnecessary for Sencha to provide Sencha Touch, which mainly just supports touch -based apps and only for mobile devices running Chrome based browser then provide Ext JS, which supports no touch-based events but can be run on almost anything.
This is bad for the developer trying to make an app that will run on all devices which will support touch-based technology and mouse/keyboard technology (But the biggest part is that this is where the world is heading towards, Windows 8 is a good example as they're almost entirely touch-oriented further encouraging the drive to touch-based alternatives)
This isn't just inconvenient for the developer but it's also inconvenient for Sencha, apart from Sencha touch have it's differences, most of it is the same. This means when you create new documentation for one product you also have to create the same documentation for the other product, minus a few differences. This has to slow down development or prioritize one or the other.
Sorry for such a long post but instead of just suggesting that they merge, I decided to give several reasons of why and how it could benefit Sencha as well.