

More realistic - when you're walking around your own town (you, not a player in a game), you can't see what's going on inside all the buildings - you have to walk into them to see.Also, if I want to have autoruns or parallel processes happening, or different BGS, based on being in a particular house, it's easier to do that if it's a separate map - otherwise I have to use conditions to say when it's to start and stop running. Limited number of events - if I have all interiors visible, that means I have to have all events in those buildings on the combined map as well.Means I have to do more work to make the outside look good, and the player has to do a lot more walking, which can just be annoying sometimes. I also don't want to have a massive map just because I have larger interiors. This is similar to a world map that has a city represented by 4 tiles, but when you enter it, it's 50x50. As long as it's generally the same shape I don't mind that the sizes don't match - the proportions are usually pretty close though.

Proportions are flexible - I can have a house that's 2x3 tiles on the outside map, but is 8x12 tiles on the inside map.Keeps your interior & exterior tilesets separated - trying to combine them means using up more space in the tileset, so you might run out of places to put all the tiles you want to use.
