Explain why "The Road Taken" would not be a suitable title for the poem.

This is an interesting question because most people pay attention to the end of the poem, which talks about the road that the speaker did take...

To me, the reason why "The Road Taken" would not be a suitable title is because the "The Road Not Taken" adds to the meaning of the poem by emphasizing its contradictions and uncertainties.

The poem is talking about how all roads essentially are the same and we only convince ourselves that they are different.  The title of the poem interacts with the text to show us this idea more clearly.  The poem talks about the road the speaker did take, but the title talks about the one he didn't take.

This, to me, adds to the sense of ambiguity about the poem -- the idea that all roads are the same even though they look different to us and we think they are different.  If Frost had called it "The Road Taken," of "The Road Less Traveled" the title would make the poem seem more certain and less ambiguous.