I see two benefits:
- Scripts usually do not need to be compiled. Sometimes scripts can be re-loaded into a running game and changes can be tested from within this running game.
- If you want the core of your game closed source, but allow modification or expansions, scripts will allow users to do that without need to have access to the core sources.
The latter point may even be useful for open source projects as a hint for mod-makers, like "This is the part that is meant to be modified" and "This is the games core, do not touch unless you know what you do".
But that is definitely more geared towards commercial/professional games than roguelikes which are traditionally open source.
A further point might be that often the scripting interface is quite high level and game specific, so that scripts are an easier way to control or expand the game. But this much depends on how the interface is made, and how high level the core is - that might be equally high level and then scripts do not have such a benefit.
