Earlier quoted context omitted.
Nothing against wood, really. But if you've been to the UK, you should agree that the unmaintained, not-properly-fitted, wooden frames that they use in most old windows are just crap. They let in huge amounts of wind, cold, etc, through the unsealed seams. Anything that improved that would be 10 times better, regardless of the yellowing, etc.
Most wooden sash (I assume you're talking about wooden sash) were properly fitted at the time, but are victorian or edwardian and therefore over 100 years old. They've done pretty well considering their heritage. New wooden sash with double glazing are better IMO than plastic windows - as the parent noted, plastic doesn't do well long term when exposed to light.
Really, I couldn't care less if they replaced the frames with wood or whatever, as long as they made sure that they were thermally good and avoid wasting all of the heat...