I'm not sure exactly what you mean by "integrate Cordova in to Construct". The runtime already integrates with Cordova by using Cordova-specific features where available. I could copy-paste a bunch of Cordova files in to the Construct installer, but then specific C2 releases ship with specific Cordova versions, which slows down the whole update process. A nice thing about the fact Cordova is not directly integrated is whenever you go to a build service like the XDK or PhoneGap Build, you get the latest and greatest Cordova version with all the latest bug fixes and features - not whatever version happened to ship with r216 or whatever C2 version you happen to be using at that time.
As has always been our policy, we do not obligate ourselves to support third party plugins in any way. If there are specific features you would like to see integrated as official features, please do suggest them.
I guess we could run our own build system, but that is very time-consuming, difficult and expensive to run, and currently the Intel XDK provides that for free. So I don't see much point in us doing that either. I know there are several build systems to choose from, but I see that as a good thing: it protects you from any one service shutting down/hiking prices/otherwise making themselves not useful. We've also been criticised in the past for relying too much on one service, so...