Is it reasonable to replace windows with double-glazed insulating glass?

Hello everyone.

I took over my parents' house in 2017.

The original house dates from 1935.
The entire house was extensively renovated in 1994. Then, in 1994, an extension was insulated according to the insulation standards of that time and attached to the house.
In the new building, wooden windows with double glazing made of Meranti were installed in 1994.

In 2017, I had all the windows in the old building replaced with new double-glazed windows.

Now I am considering whether to replace all the remaining wooden windows installed in 1994 with new plastic windows.

The windows still look really good in terms of material and there is nothing wrong with them. One window does not close 100% tightly, but nothing has been adjusted for 20 years.

I have now had four companies here. Some say they should definitely be replaced, but one company also said that the windows are still in good condition and just need maintenance. That one window would close tightly again if adjusted.
He also told me that if I replace all the windows, what I save through lower energy costs might only pay off in about 25 years.

Costs would be around 12,000 euros.

Can you say anything about this?

I would appreciate any tips. I am attaching pictures.

If nothing bothers you about the windows, otherwise I would leave them in until they are worn out ….