Hi,

Yes, User Experience is important and become easy with the Framework as the Framework takes care of a lot things via inbuilt methods/features.

Also, the state management become very difficult even for a small web application without frameworks, please consider the related blog on this, https://medium.com/dailyjs/the-deepest-reason-why-modern-javascript-frameworks-exist-933b86ebc445

When it comes to Single Page Applications and concepts like Routing,Bundling etc. comes into picture, it is more or less very difficult to manage with even vanilla JavaScript itself.

Regards,

Jakes