* Many experiments and a lot of science cannot be done from space, even if delivery costs were much cheaper. E.g. LSST (0.5 billion in US funding alone, + lots of other funding sources), or wide-field astronomy important for near earth object detection and monitoring (e.g. ASASSN). These things are too complex and too large to realistically do in space.
* Ground-based astronomy is inherently cheaper (no space costs, no extra engineering effort, and importantly, the ability to fix things and upgrade equipment), and therefore has a much lower barrier to entry. You can do truly meaningful research from the ground for ~$1 mill + a team of 4 or 5 core people, whereas space requires 10-100x this + an entire fleet of people with all of the associated bureaucratic nightmares + extra time required and engineering challenges. Space offers some benefits, but often times the tradeoff is either not worth the cost, or the experiment is not feasible to do in space.
* Regardless of whether or not you care about the impact on astronomy research (hey, astronomers care about humanitarian stuff too), the way SpaceX bowled through and just started launching their Starlink constellation was irresponsible, reckless, and actually quite ignorant (e.g. they were surprised by how bright their satellites were...this is basic stuff people). On the other hand, I'm not sure how much blame you can really place on a company being reckless when the law allows for such recklessness. There should absolutely be more regulation and oversight. It's in the governments' best interest because it's going to just destroy (needlessly) a lot of R&D already paid for.
Ninja edit: mentioned Space-X in here but this article is technically about Amazon's Kuiper constellation; however statement is the same (this isn't really a single company problem, this is a new-technology-without-appropriate-regulations-problem). Starlink is the largest constellation and the biggest problem (planned to have ~10x the satellites as the Kuiper constellation, they are lower orbit than anything else, and not sure how the albedo compares to Kuiper, but the brightness is > 99% of other satellites).
So: these constellations will multiply number of orbiting satellites by 10-100x, they are extremely bright (> 99% of all satellites), and they are very low orbit. So its a perfect storm of problems for astronomy.
final ninja edit: check out https://www.astro.princeton.edu/~gbakos/satellites/ to see one astronomer's page about this stuff, some actual images that illustrate how big the problem is with the extremely limited amount of starlink satellites currently in orbit, and some other links. OK that's all