The devs working on news sites understand the current state of bloated pages is bad and are eager to create fast, sexy pages. Unfortunately there are entities such as BizDev and AdOps that want to add more stuff to the pages to make more money, and it's easier to quantify ROI for a new ad placement compared to shaving 100ms off page load times. So we end up with dozens of scripts and script loaders and all sorts of other things. Editors and product managers want responsive pages with ad placements and enhanced functionality.
Along comes AMP, and all of the above are freaking out at the loss of control while I'm gleefully looking at super fast loading times and pages that still have most of the important functionality and ads.
Yes, the script size is large, but it will be cached amongst all AMP pages and it's refreshing to not have to think about implementing responsive pages, lazy loading, etc. because AMP handles all that.