Agree that they need some better options. I think fit to fill would cover more bases. I often have the opposite problem where 4096x2160 footage will result in a silly amount of letterboxing in a 16:9 sequence.
I had to deal with this on a 1920x1080 timeline where someone had filmed broll all in DCI 4K, which meant it was scaling automatically to 46% instead of 50%.
Surprised this is still not yet a feature (or, preferably as suggested, "touch from inside" / "fill frame"). This is basically a Windows 95 wallpaper level of functionality! 😁
In the meantime, is there another way that I can achieve this in Premiere? (E.g. a preset or some kind of script?).
I had thought about, e.g., creating a Photoshop action for batch processing images I use to 2160 height, and then a Premiere preset for scaling them to 50% -- but this is a little messy from my perspective (and I'd prefer to have the performance benefits of working with smaller images / no-higher-than original pixel density where possible).