In my opinion Cocos team is in the right direction (although when I have seen first versions of Creator I was very skeptical if they make it good)..
I would never write my own IDE in Qt today. Best IDE I know are written in Java (PhpStorm) or some own framework (Visual Studio). I have been working with Telegram Desktop source code (written in Qt) and some older experience in Qt, and I do not want to go there. It reminded me when I was making my first windows apps in 99. So old school and heavy.
If today I am going to write and IDE or any other crossplatform app I will without any doubt use Electron. Moreover, I will use Typescript + Angular + Electron. Example: Visual Studio Code was written with pure JS and Electron.
Looking at changes that Google and others make, I can say that ECMAScript 2015-2017/Typescript is language of the future. First of all, huge development in progressive web apps (PWAs) -- check out how much of Google IO is devoted to web programming and native using webtools. Huge increase in Angular/React frameworks, many cross-platform stacks are formed: Ionic, NativeScript, Cordova.
If you say that JS is slow, then Battlefield 2 and Eve online was written in Python (Python, Carl!) How much it slower JS? Even my company writes IoT devices with Python... and that's more than enough from performance point of view.
Thus normally, JS is more than enough for any game, given that most time critical tasks are done with native API calls, so outside of any script language. But returning to cross platform Ionic is more than enough to write any mobile app in pure JS without any native implementation, if that is not enough for you you can use NativeScript and it will produce native performance because the app is not anymore on top of simply webview but behind the scene render is native and all your calls are bridged to native calls. So writing natively with JS for any platform? That's where Google, Microsoft and other big players going.
Node.JS. -- just one thing that makes JS development great (and thanks Cocos went this direction). You can find any package there install and use. Recently in cocos creator I created typescipt project and want to work with Dates... OK... npm install --save moment... next I want reactive programming... ok ... npm install --save rxjs, etc... This things make development start really fast. One grand benefit.
I still believe that Cocos Creator needs more, but in current condition it is great tool already. They use bindings for JS calls, but if they could choose same approach as NativeScript it benefit more (also I miss dependency injections in constructor, that part of Angular is more powerful).
They need more smart way of working with animations (currently it is only one way to create animations and it is not straightforward).
I do not want to return to C++ after Typescript. And I definitely cannot survive without Node.js/NPM packages.