Since hard disk space is cheap, we litter old tools in carefully protected directories, just in case they'll ever be needed again. It drives our code guardians out of their minds. The right thing to do technically speaking would probably be to rebuild all the old stuff. The testing alone consumes vast amounts of valuable development time. The risk is high, the benefits are vague.
Most tools require some level of attention and management.
Someone, or some group of people, have to keep all electronic tools metaphorically sharp. Take for instance a PCB layout program, a staple of every engineering department. When our vendor recently released a major upgrade to the PCB software, we discovered to our horror that all of the libraries were now obsolete. Now we have the great joy of maintaining both old and new versions of the software. One friend addresses these sorts of problems by never upgrading.