I think I don't want the apperance of my app to be ruined by the user or ugly themes. Especially when I do some grahic stuff.
What about users, who don't want their look and feel being ruined by
your ugly app?
But your oppinion leads to the fact, that the most lazarus applications have the same design: a no-design.
Exactly. This is called system-wide widgetset, UI unification and respect to users.
My opinion, neither yours, doesn't matter. User's one does.
And he (user) already picked a suitable OS, look and feel theme, fonts and stuff. At least he's accepting it.
So respect it. If you want to promote your very personal point of view about "what beauty is" - make it optionally customizable.
I'm also developing an application where customization is a must: an owner-drawn timeline-like control, where font size (kerning)
should be appropriate with other box sizes in pixels.
A TFontDialog and Inifile is doing that simple trick.