Hey I know this is a 3 year old post about a 5 year old game, but I was looking for this answer myself and it seems nobody has found/posted one yet. But for anyone like me who happens to look for this, I think I found how to do it.
In world.gdb are all the different areas the game generates. Look for:
"BlockTypeIndex 1 // Deadend
And change the BlockTypeMult to a lower number, or 0 if you want.
Then do the same with:
"BlockTypeIndex 7 // Open all sides"
But increase that mult.
You'll have to do this dozens of times. Use ctrl+f and replace.
On mine, I only did this with the overworld areas, not the dungeons, as I feel those are okay as is. I was just too tired of the claustrophobic mazes out in the middle of nowhere. I changed the deadend mult to .5, and the open all sides mult to 3, and that seems to be much better. You still get some of the silly outdoor hallways, but much less of a headache. Hope this serves you well, whoever is reading this months or years from now!