That's a good thing.
> or Mac OS X
"Does Winforms run on OSX?
Yes, as of Mono 1.9, Winforms has a native OSX driver that it uses by default"
> it looks completely out of place on Linux
On KDE3? KDE4? KDE Plasma? Gnome2? Gnome3? MATE? Cinnamon? LXDE? LXQt? Xfce? CDE? GnuStep? Unity? Enlightenment? Non-DE X Window System environment - with which Window Manager, with which theme?
> In terms of integrating visually with the desktop, we currently ship with a classic Win32 theme.
That sticks out like a sore thumb everywhere, including every Win32 release since Windows 2000.