Maybe all of them are valid, but there are other, equally valid points for continuing to use these cycle-rickshaws: they are non-polluting, they can be used far more effectively for short-hauls than any motorized option, they provide employment for many who are unskilled... all of it going to show that the 'man-powered-carriage'(*) can still find a niche for itself in this crowded city.
These rickshaws are filling one such niche. They are waiting, close to the Chennai Central railway station, for folks who cannot afford any other means of getting to the closest lodge after a long and tiring journey. In many cases, these newcomers to the city have wrenched themselves away from their native lands with all their possessions and this is the best way for them to soak the atmosphere of a new city, while they seek out the most economical lodgings. In the meantime, there is also a proposal somewhere in the works to have a bunch of cycle rickshaws traverse the Marina, as an attraction for the well heeled tourist who wants the 'experience' of travelling by the rickshaw!