I really enjoy how most of the abstracts in these papers are more like ELI5s, or just plain understandable. I think having an understandable abstract would be valuable for many papers to have to make large complex sciences understandable for people not in the field. Would there be any downside? The only one I can think of is that conclusions could sound more convicting in a simplified summary.
Having understandable abstracts is indeed very important for the success of a paper and scientists try very hard to come up with good abstracts. Writing the abstract is one of the harder parts of writing the paper. However, what you find understandable and what an expert in the field finds understandable is often very different.
