This is called “end point fallacy” and is common in facile analysis of transportation plans.
“Why would I want to go from <end of the line> to <other end of the line>?”
Most people don’t, but will use the many other trip pairs along the way all the time.
It takes 11.5 hours to go from one end of the Shinkansen network to the other (Hakodate to Kagoshima). Nobody in Japan makes this trip except as a stunt; if you need to go from Hakodate to Kagoshima you'll take a plane. And yet, HSR is very useful for Japan...