If you back your case against change with real arguments (like “There will be massive downtime.” and “Extra maintenance will be necessary.”) you certainly aren’t naïve. But you are very naïve indeed if all you ever say to anyone proposing any change to working systems is “If it ain’t broke, don’t fix it!”
Agreed. In reality, there's a balance to be made between the cost of maintaining the status quo (in the event that the status quo sucks) and the cost of making changes.
One thing that really frustrated me when I started my career is that the cost of making changes turns out to be non-trivial. If you're shipping software to customers then making changes to the software involves a lot of work planning testing, packaging and so on. Maybe that's one of the reasons why hosting web apps is so much easier than selling shrink-wrapped software in a box.
