Equipment has a development life cycle. Even things developed with 'new' hardware, takes 3 to 6 months to be available for 'product engineers' who put in 3 to 6 months before a product is available for 'public consumption'.
.
More complex/sophisticated/environmentally robust equipment take much longer. Getting new avionics is a 3 to 5 years cycle. It even takes the military 3 to 10 years to get development done for earth bound hardware.
The Nuke industry/govt agencies require 'hardened' hardware, that takes about as long as getting military OK for use.
Space craft life cycle, to keep from continuously re-engineering the same system many times before the first flight is 'frozen' at a stage that seems way to early in most venues. But that is what has been found as needed to be safe and reliable. It also becomes a 'religious issue' about not touching systems once they are 'flight ready'. Many of the designs, since they are 'one off' are not designed to be upgraded, at least not hardware wise. Even software upgrades are hard due to the 'flight ready' validation process. So unless a 'mission critical' need for 'uber new' hardware/software is found, it isn't going to happen (at least not in any 'market speed' speeds). So yes, we fly 'ancient' but reliable hardware.
How to get around this? Go work for NASA, get more funding, make it a priority to fly 'less outdated' equipment. I watched John Glenn go into space on TV. I watched the first foot steps onto the moon, live. I am proud of every step we have taken.
We have had very few pay the price over the years, and part of that price of keeping the payment in lives low is flying over-tested, over-worked, over-priced, outdated hardware.
I do want to fly newer equipment, but I don't want less safety. Flying fewer manned missions, and more 'robot' missions with newer hardware is one choice, but I don't want to give up on manned exploration. (Before the haters chime in, man in this case is mankind, being inclusive, not exclusive, in gender, race, etc. I do dislike feeling like I need to include explanations whenever I use words correctly, or having to be PC otherwise.)