(disclaimer: I work on the Flutter team)

We certainly don't think Flutter should replace HTML or other frameworks. We hope Flutter will work well for many use-cases, but the web is huge. There's room for multiple approaches. If it's not working for your use-case it's totally fine with us if you use something else. We welcome constructive feedback on what's not working so we know where to focus our efforts.

Thanks! A great first step would be to have a "web-native" renderer for your web version. Meaning that it'll use DOM elements that the browser to handle the rendering of. Would fix many of the current issues with your implementation.