Edit: Actually, stumbled on some info recently, and it seems this may be easily tweakable. Keep an eye on future releases.
Limitation of the engine, unfortunately. Keep in mind that the save files are just that, however. If you really want to, there's nothing stopping you from creating a block of them, copying most into a sub-folder in the save folder, and then continuing on to create a new block. Bit of a hassle to swap the blocks out, but better than nothing. In the absence of that, I'd recommend saving only when you're about to do something potentially risky, and having a revolving "progress save" as you work your way through a given combat map. Although there are a few surprises, in general I try to signpost major events somewhat.