When new facilities get added, you change with the times & do not stick to history or heritage.
Earlier, all trains from TCR side used to go to SRR, reverse & carry on to PGT side. Subsequently bypass came into existence. So most of the trains skipped SRR and moved to PGT through the new line. Same is the case with NCJ, where most of the recent services b/ween TEN & TVC run via NJT & not NCJ.
To cut a long story short, such developments keep happening everywhere; whether to...
more... cut running time or reduce crowding, diversions, change in terminal, extension etc of trains too keep happening. Feel it's better to adopt & accept these changes than demanding that those trains running earlier should come back. Also, why is this principle not applicable to gauge converted PGT - POY - PLNI sector? How many of the trains running during MG era have been reinstated till date?
As far as CBE - PGT MEMU is concerned, don't think there's any dearth of passengers in it even now. Still if you are certain that its patronage will further improve through diversion via POY, should certainly take it up with those concerned & get it implemented! Same holds true not only that MEMU, but get all such trains which have a chance of getting better occupancy re-routed via POY.
To the best of my knowledge, the current CBE - RMM is only a special train & not reintroduction of a service which operated during MG days. If so, it would've ran daily & not this way. But, if it indeed is a reinstated service, it should operate though the former route(but then, same holds true for erstwhile services in PGT - POY route as well). However, if it's a new service, then it is a different matter altogether.
You may not find any train to MAS skipping major cities after CBE, as there are no bypass lines available ahead. But if you take IR as a whole, there are many trains skipping prominent cities enroute for operational convenience. So genuinely feel a sensible move will be to double the line between PTJ & IGU, instead earmarking it for Goods traffic. Once line capacity increases, obviously more trains will start running. Will it not suffice if those trains skipping CBE halt @ PTJ?
Finally, request you not to underestimate a major city like CBE; it is capable of garnering sufficient revenue to stay A1 without depending on nominal income from a train like 12623/24!