A way to import other SVG files in such a way that they remain "live".
A logo in one SVG file. The application of that logo in various other
files. Logo needs a change? No problem, edit logo.svg. All the others
(when they are converted to PDF or PNG or when opened) will now have the
Multiple page documents.
A way to spot-export to PDF like you can to PNG [*]
[*] Which itself needs work. Right now you use a layer and you draw
boxes on it, you give them an id, you select one (or more) and then you
hide that layer. Then you export to PNG. It's weird, but it works.
A way to bring Gimp XCF files in. With layers (as far as poss.)
A way to show some layers/elements by outline-only while others are
shown as basic fills. The all or nothing view modes are fine, but
complex drawings are still too slow.
A way to show large blocks of text as grey rectangles - for speed.
A way to kern entire text areas at once!
Colour symbols. I don't know the right phrase.
Example: you use orange in your drawing. Later you want to try pink
where that orange was used. You change the orange to pink. It changes
Custom palettes. A way to make my own colour collections and families.
Extension to this:
Share palettes across multiple svg files. Change colour once, update
everywhere (across files).
Swap out one family for another - entire drawing changes to new colours.
This would let you change the mood of a work very quickly.
Interactive, on-canvas, ways to explore colour.
Example: Drag from the colour-chooser to the canvas. A swatch appears.
Drag another out. Dropping it creates interpolated swatches from the
first one. Dragging the end-points makes more room for more interpolation.
Grab all, or pick a few -> add to palette.
How about a live way to see what colours look like to colour-blind eyes?
Connect swatches to each other through "recipes" such that you get a new
colour. One such recipe could be "Tritanopia". In one you see green, in
the other swatch, grey.
In complex paths, when in the edit-tool, don't draw all the handles!
i.e. some way to draw only the handles that are near the mouse pointer.
The speed of Inkscape is dire when thousands of handles are drawn and
then, dog forbid!, you scroll the canvas or zoom! Arrrggh!
Enough wishing! ;)