Something else to remember, the Republic stood for thousands of years. One culture for longer than there's been any on this mudball, I would quite imagine that once they found a design that provided the requisite capabilities, they would keep it. Image is powerful, and if you can present the same image for long enough, even if it's untrue, it still instills a level of comfort and respect.
Also, they were at the peak of technological development, more or less, Type 2s have more or less learned all there is to learn, from a practical stand point. There will still be development, but it won't come in fits and starts like it does with us. It will come in refinements of what there already is until it's unrecognizable from what it started as.