The discussion has come a long way. I am entering in the middle and hence may be coincidentally repeating some of the earlier viewpoints also.
I find the discussion #611671 by Gokul Aravindh quite comprehensive and having some relevant points.
In India we got to have a discussion about this matter when Indira Gandhi was the Prime Minister and was at her peak of power and facing strong criticism also. Post Emergency during the seventies, there was a feeling that India needs a benevolent dictator.
I am of the opinion that we as large country and also having a large population united by national and patriotic spirit, but having many day to day difference in language,weather,food habits,etc, cannot have one person as the decider and implementer for the country as a whole.
In India we cannot be adamant to be having uniformity, but we are having Unity. We are the union of states. Our central government is called Union government.
Unbridled power in the hands of one will lead to the situation of proving 'Power corrupts,absolute power corrupts absolutely. Anywhere in this world, countries who have or had such unitary Heads with unchecked powers have either collapsed or disintegrated or have been experiencing internal chaos and civil war.
Thankfully, our leaders of the freedom movement had deliberated thoroughly and given us a very comprehensive system of representative democracy, where neither the Prime Minister nor the Titual Head President have any omnipotent powers. However Indian President has sufficient powers to rein inthe cabinet or legislatures when they go against the spirit of national unity or hitting at the fundamental rights and natural justice.
So, having time tested for the last seven decades, at the same time having seen the defects of Presidential system in many other countries leading to collapse and chaos, I do not see any need to change our present system of Parliament, Cabinet and Prime Minister headed by the titular Head President.