Should suburbs get an underground metro line?

IIT's report on the crucial transport link has bolstered their case, say Mumbaikars.

The metro is being designed for the convenience of the people while commuting. Vehicular movement by road is tough because there is a limit to expanding motorways and population is increasing. If the metro is constructed overground, it will lead to constricting road space and there will be no further scope for expansion. MMRDA's plan has no vision and is too expensive.   
—Divya Gupta

MMRDA's plan to make an elevated metro is not a feasible option. It will increase the suburban road congestion, where everyday people struggle in traffic chaos. An elevated metro will aggravate the problems like noise pollution, encroachments, cutting of greenery and residential tenements. If the metro goes underground, then there are chances that there will be relief to the city. Moreover the city needs a plan which gives a long term solution rather than one that creates a problem.  
 —Jyoti Gujaran

The IIT's report has various valid reasons, while MMRDA is neglecting the views of people and behaving in an autocratic fashion. Overground metro is going to demolish many residential and commercial buildings. Secondly, there will be no further scope for easy commuting, for motorists, on the road in future since elevated metro will limit expansion of road space.
—Amrita Krishna

Mumbai shouldn't be compared with other cities, which have an elevated metro. It might have worked for other cities since they don't have paucity of land. Mumbai is densely populated and lacks road space. An overground metro will mean that houses, commercial buildings and trees may be demolished. Moreover, traffic congestion is not going to be solved even if the metro comes in suburban areas. The felling of trees doesn't augur well for the city which already lacks green cover.   
—Bablu Rajak

Even a layman can tell the numerous problems associated with overground metro plan. Firstly after the metro is constructed, it's not that people will stop travelling by buses or private vehicles as metro might not be affordable for everyone. People will still travel by taxis, autorickshaws or private vehicles, they will need the road space that the overground metro will gobble.  
—Ameya Gore