Governments must always balance demands for newer modes of transport, including newer railway lines to connect cities, with maintaining current transportation infrastructure. In my opinion, the maintanence of current transport has a greater overall impact although the importance of fast trains will make life more convenient for commuters in the short-term.
Whether a significant amount of money should be disbursed on constructing new railway lines for fast trains or if it should be spent on improving existing public transport is a highly debatable topic. While some people advocate for the construction of new railway lines, others argue that the money should be spent on improving existing public transport.