Well, I don’t know where you’re getting your images from, but they look like they have a lot more pixels than mine. For example here is the scale icon bitmap from V7 at 32 x 32 px - the result does not look like what you posted above.
I was mainly interested in seeing if it worked to quickly convert some bitmaps from V7 that I had modified in Photoshop. For that the result is OK I guess, but in the end using the original bitmaps at that size doesn’t really look worse. The main problem is you can’t import the bitmaps themselves into a V8 button, you have to import the whole button or toolbar from V7 in order to keep the bitmap.
Well, maybe the Mac Rhino icons are different (higher rez?) - I was exporting the bitmaps directly out of the V7 Windows Rhino button editor and the max size is 32 px.