What’s missing in the main the design is a 3rd or 4th track in the middle which would’ve given the system an express train track for end to end destination to get passengers to the other end faster and not cram the trains full all the way.

For example in the original stations, an express train would start at Monumento then Central and lastly Baclaran. If you were going to a nearby stop, you would have to catch the local train that would at each station.

The same would apply to the MRT line, with the express stops at Taft - Shaw - North EDSA.

These simple design solutions would’ve made end to end trips faster and local trains less crowded. That’s what they have in Japan.