EDIT Thanks to the latest update, we can now make traditional spritesheets with Spine. See the screenshots Nate posted below for where to select "grid" as packing option. Thanks to Nate for the extremely prompt reply here and feature addition!

I've seen a couple posts here mentioning spritesheets here and not being able to use them as expected in various 2d engines. I think what isn't getting through is that a spritesheet != a texture atlas. Many simpler 2d engines that don't employ atlases or even GPU rendering expect a spritesheet laid out as in a grid without an associated data file describing the regions. Just a grid of frames of equal dimensions, laid out in order from left to right, top to bottom.

You can almost make Spine's texture packer behave in this way, by unchecking all the whitespace stripping options, but the resulting sheet is still laid out un-ordered. Well not completely un-ordered; I think the problem stems from Spine not putting leading 0's on its region/frame names, so when assembling the atlas and data it goes 0, 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 21, etc. Simply adding the leading 0's might automagically create a usable spritesheet maker, at least on a per-animation basis. Tracking down where one animation stops and another begins would be trivial if they were numbered correctly.

My workflow previous to using Spriter was to export frames from TV-Paint, and then use ImageMagick to make my spritesheet. Even that solution won't work here, due to the leading 0's problem.