You have made it an either / or situation. It is not.If speech is subject to restrictions by morality, then its not "Free" speech anymore is it ?
Anyway, to the point, There is great power in Symbols and iconography. But nothing beats the real thing.
I can give you a fantastic icon and symbol of a 10 course meal or I can give you a free meal, what would your prefer ?
What would the citizens of mumbai prefer ? what would be more inspiring ? Huge clean roads and world class public transport system or a huge statue ?
Focusing on symbols and iconography is to miss the forest for the trees.
What Mumbai desperately needs is uninterrupted water supply to house holds and basic sewage and drainage lines to each homes.
It needs world class public transport system.
It needs enough world class schools and Play grounds for kids to play and develop.
It needs a green cover and pot hole free roads.
It needs FOOTPATHS and enough parking space.
To replace all of this needs with a statue is a joke.
You are extrapolating. The money will come back to Mumbai from increased footfalls and revenues.
Lastly, what do you mean 'ask the people of Mumbai'. It IS the people of Maharashtra making this decision. The elected Government of Maharashtra is making this decision. There need not be a referendum each time an elected Government takes a decision.
If you don't like it and if you are a voter of Maharashtra, vote out this Government. If not, then.....deal with it.