I've never been in a game where I ever thought "yes, random encounter! wooo hooo!"

It's just a workaround for games that for whatever reason can't show enemies in the field. Either because they can't make it work with the level design, AIs having problems navigating the area, or something else.

Any Gamebryo game can tell you that you can dynamic encounters without having a jrpg-style battle screen or enemies popping out from nowhere.