Long distance EMUs are becoming more popular as technology improves and the electronic components can be made smaller. In a separate locomotive there is a lot of room, but in an EMU you also need to fit the passengers. read more
Suburban EMUs might also use direct current at a relatively low voltage (700-1,500 V) which is good for shorter distances and low speeds. The construction is lighter when built for low speed, since the collision forces in the event of an accident are much smaller in lower speeds. read more