Some ideas I think would be helpful:
A way to auto-generate slices based on all (or selected) layers
Using layer’s x/y and w/h, you could easily generate a slice for each layer.
Parenting / locking /grouping slice(s) to a layer so that they move around with it.
To avoid forgetting slice relationship and save time arranging things.
By checking if the slice is parented to the layer and is also the same dimensions as the layer, duplicates could be warned/avoided when auto-generating again.
Multiple UserData fields per slice
This would allow for adjustment of particular UserData field to multiple slices at once without erasing data kept in other fields (rather than using one field for multiple purposes.)
Would be very useful for moving slices between open files in Aseprite rather than remaking them, especially if they contain Pivot, 9-slice, UserData.
To see a layer’s x/y position and width/height when selected
Seems like this info isn’t visible anywhere.
To export layer x/y, w/h, and UserData
For some people, just being able to have this layer info exported to file would be sufficient, thus skipping the need for and work of making slices.
Thanks for your consideration!