Re: Telescopes should be in space and not below 100km of atmosphere.
"It's instructive to compare the history of the James Webb "
The problem with spacecraft is that launchers are sodding expensive.
Which means you only get one launch and one spacecraft, (and maybe a backup if the first goes bang)
Which means you heavily invest in making sure your spacecraft works
And also means that you add every bell and whistle you can think of to your spacecraft, because you only have one launch
Which puts up the launch mass and complexity
Which means you need to invest even more heavily in making sure your spacecraft works
Which means you build hundreds - if not thousands - of test articles
Which means in the end, your spacecraft is valued in $billions, but only has an actual materials cost of a few million - and you have a backup in case it didn't fly - and if you wanted to build several of them you'd be able to without even making much dent in the project budget
Except that doesn't happen
Because space launches are primarily a dick^H^H^H^Hflag-waving exercise and the science is in a distant second place by comparison to the "Gee, aren't we great!" behaviour when the thing is launched.
And space launches are like that because they're so sodding expensive.
Cheaper launches means simpler payloads are more easily justified, and really cheap launches means you can even afford to send up a dud occasionally without it being a career-ending move.
And it might even mean that development moves fast enough that a mission might actually take less than someone's entire career from first concept to actual use in space (seriously - taking 20-25 years from inception to launch is par for the course. There are several spacecraft sitting around that were completed and have been waiting to be launched for 20+ years, thanks to "funding issues" that cropped up along the way.)
James Webb is a good example of old-school thinking. It's big but hideously complicated because it was _too big_ for any existing launcher when first designed. The fact that better/bigger launchers now exist hasn't caused a redesign, but a redesigned JW might be flyable sooner because the single most problematic part of it is the sunshade and those problems are vastly reduced if you can have more launch mass and/or payload volume to work with. (The foldout mirror wings is another issue but not as problematic as the sunshade)
With something the size of starship, at the price of starship you could launch something like JW in two parts (instrument and sunshade/spacecraft) mate them in orbit and send them out to L5 with a tug sent up on a 3rd launch and STILL have change leftover from the cost of the original project.