Textual words from them:
It’s our first step towards a more modern, more beautiful, and more customizable Thunderbird experience. We think you’re going to love it, and we are endlessly grateful for all of your support throughout the years 💙
is that too much to ask?
Let’s say it’s a lot to ask, especially when the app also needs to be crossplatform and behave functionally the same on all platforms.
Maybe it could be done, in theory, with a lot of work, but it’s definitely not at all an easy task, especially for a project that seemed dead and buried just a few years ago and with just a handful of volunteer devs.
Most crossplatform apps that I can think of don’t really look like native apps in any system. I’m thinking of Chromium, VSCode, Discord, Steam etc.
The only one I can think of right now is Whatsapp, but I’m pretty sure they actually developed three independent apps and maintain all three, for Android, iOS and Windows. They all look and feel like native apps because they are. Please tell me if I’m wrong.
Still, you can’t expect all, or even most developers to do something like that, especially when you start including all the different DEs and themes and so on.