Personal preference for a theme should have little if any impact on
Emacs defaults, as (at least on my OpenSUSE KDE desktop) Emacs
is a proper citizen and follows my global theme.
The only thing that doesn't follow and which I like to use a custom
theme for is the modeline.

On Sunday, 6 September 2020 17:00:39 CEST Elias Mårtenson wrote:
> On Sun, 6 Sep 2020 at 22:45, Alfred M. Szmidt <ams@gnu.org> wrote:
> 
> >    1) Improve the default theme: Maybe set a default dark theme to make
> >    emacs feel more modern. Experienced users usually already have a custom
> >    theme, so they won't be affected. There is actually some statistics
> >    about downloades themes here:
> >
> > This would be an utterly disastrous change.  As an experienced user, I
> > do not have a custom theme, and prefer to use the defaults of Emacs.
> >
> 
> Same for me, and I'm pretty sure we're not alone.
> 
> Also, while dark background is popular right now, it's not necessarily
> better. Apart from the fact that there is actual science showing that dark
> backgrounds are worse for one's eyes, I believe the current trend is merely
> the pendulum is swinging back.
> 
> Recall that backgrounds used to be dark back in the terminal era. Then
> monitors became better and white background was finally usable. Now, people
> who only ever have experienced white backgrounds wants to change things for
> the sake of change, so that is now popular, even though it's actually
> quantifiably worse.
> 
> This Wired article on the topic contains links to actual research on this:
> https://www.wired.co.uk/article/dark-mode-chrome-android-ios-science
> 
> Regards,
> Elias
>