According to me, the concept of MEMU Express is very bad. Passengers who r not regular travellers get confused seeing a MEMU rake, they think it is a passenger train but if caught by TTE they have to pay penalty. If not caught then loss to Railways as passenger travels in Express train with Passenger train fare maybe sometimes unknowingly also.
If aExpress give Conventional rake , if Passenger train give MEMU rake. Make it simple. Convert all conventional passenger trains to MEMU rakes but not Express train rakes