Even when looking at the Wikipedia article there’s way, way more written about the first 200 years, then the next 300, by a lot. Most of that content is about Diocletian and Constantine. There’s hundreds of years of Roman history that are basically glossed over. For some reason everything after Marcus Aurelius is significantly abbreviated, even despite long serving emperors like Septimus Severus coming right after.
Is there any reason why most of the history after 180 ce is glossed over?
I think the answer is historians know more when they have more sources and less when they don't, and sources from the ancient world have survived to today pretty unevenly. Here's an answer from u/Alkibiades415 that discusses why so much is known about some parts of earlier roman history than later parts: https://www.reddit.com/r/AskHistorians/comments/v6x4kr/why_is_the_period_from_the_1st_punic_war_to_the/