Currently when you export to PNG it exports as a full 24-
bit PNG file. It would be nice if it were possible to have a
few more options when exporting to PNG, to be able to
export as 8-bit indexed, greyscale, B&W, etc., as well
as to choose whether or not you want it dithered, how
much compression to use, interlaced or non-interlaced,
alpha channels or no alpha channels, etc.
While it is possible to just fire up the gimp and do all
these things yourself, it's an extra step or two that could
be avoided. If you're creating a drawing in inkscape you
want to use as a web graphic, it'd be useful to have all
the png settings in inkscape so you can try and get the
file as small and as efficient as possible...