Uhm...well to be honest I refit my ships a lot.
The Terrier class were on Mod1.4 (the 5th refit to the class). The BIC fleet was refit continously as new engines were developed. The Tribals will be refit to the Mod2.3 standard relatively quickly as all the modern electronics is now available, although I may delay to install also the upgraded shield generators.
Refitting the ships as you develop new technology is only sensible. With a conventional start it is going to happen regardless. The replacement of ships would result in scrapping but so long as the hull size is part of your force make up, periodic refits with new technology is to me absolutely typical.
As the game is constantly complaining about some morale error due to deployment overflow I'm scrapping older ships and building newer ones. But that is sensible enough as most of those ships have been in use for over 30 years, nearly 40 in some cases.
I also have the feeling the question must be poorly worded as I can't fathom why you would think that for 95% of the game refits are not required.
OK, I had a coffer and after reading what you wrote I understand what was wrong with my statement.
The thing I am trying to point out that it is usually more economic to scrap the ships and build new ones than refit the old ones. The cost of the refit is most of the times (95%) more expensive than building and entire new ship. Which is what I was trying to point out. In no way did I mean that refitting ships is a bad idea. I do it too despite the costs that are higher than building new ships.
In reality there are frequent refits that take place every few years. In terms of Aurora that would mean you pay incredible amounts of resources as the game almost always tells you it is a better idea to start from scratch.