ET-BPL and BPL-BINA requires separate MEMU trains that too with frequency atleast twice a day. In Morning from both sides and in evening from both sides. So extension will not do any good. But yes they should've been introduced ASAP. Maybe because Bina Memu shed is still incomplete that's why they are not asking for more rakes.
BTW 1 NR marked 2020 made LHB MEMU rake is standing in Itarsi from a month.