Yes, 93 year old water main should have been replaced several years earlier. Pipes are not meant to last that long. The cost to replace them in a timely manner would be much cheaper then to replace them plus fix all the damage that happened when it broke. The cost to tax payers, and the countless man power hours to repair the damage would have not been so much if fixed in timely manner.
I believe that in general, there should be inspections of any major equipment to make sure that it is up to code and maintained. In something as huge as a water main, this should be monitored very closely due to age. With something that is nearly 100 years old there are bound to be some sort of maintenance issues over the years. I do not agree with the philosophy that if it is not broken don't mess with it. If there were any signs of breaking down or repair work that should have been done it should have been taken care of immediately to prevent a much bigger catastrophe from happening in the future.
The really is no excuse for it not being fixed a lot sooner. In my opinion, it should have been replaced at least twice in this time. No one likes repairs and construction, but it takes place for a reason. Nothing last forever, especially not anything man made. So yes, of course it should have been much sooner.
These kinds of basic maintainance problems should be fixed immediately to avoid further problems down the line. Leaving it so long after the fact is only going to prolong the process as the materials will have broken down further and more work and expense will be required. Its not difficult to predict.
The problem with your idea is that the pipe that burst had no signs that it was damaged. Sure, the pipes are old, but old does not necessarily mean that it needs to be replaced. I have no idea how often the pipes go through routine inspection or what their life expectancy is. Usually, as cities grow, older infrastructure tends to be replaced to allow for a higher volume, and if an existing part is sufficient then it just keeps being used.
Even if they expected there might be a failure in the near future, they would have had other problems. The pipe that broke is part the key artery to the city. If they were to replace the entire older pipe, this would mean that much of the town would be without water for a very long time. The work would also shut down all areas where the pipe goes, for instance, if the old pip is under a street, highway, or structures, the streets, and highways would have to be shut down and building over would most likely be either torn down, or shut down. I am sure once they get the pipe shut down, they will fix that section of pipe and maybe do a more detailed examination of the rest of the old structure but as long as it does not show signs that it needs to be replaced they will probably keep on using the old pipe.
There are examples of pipes that have been in use for much longer than 93 years. I found at least one example that shows pipes that have been used since the 1860's and are so old, they were made of wood.
The good thing is, they have come a long way with pipe repair. They have one system that inserts a double sided expandable tube down a pipe and pours a cement like substance between the two liners to form a solid inner pipe. From what I have read, they can do lengths of up to 1,000 feet so would require less down time for roads and could save structures above the pipe.