Comment: "...several commenters opposed building a wall along the Ala Wai Canal, saying it would ruin the canal’s historic value."  

Quite probably they describe the canal with the tired and overused adjective "iconic" 

One must wonder what exactly is the historic value of a drainage ditch?  One must also wonder if those imagining such value have walked the length of the canal recently.  

For the most part it is a drab, dreary construct, it's "promenade" the domicile of dozens of homeless. It terminates in a decrepit marina that is filled with flotsam and jetsam. In the final analysis anything would be an improvement.