I live in the middle of the desert (near Edwards AFB) and I can only download 40GB/month. I think there are a lot of people who either have limitations on their total GBs OR slow service in rural areas around the world. So it's important in my mind to have a basic working version somewhere in the 1-5 GB range.
I would say there are three sizes of interest to me -
-1-5 GB download, up to 10GB uncompressed - bare minimum for people with low bandwidth/low GB restriction.
-~20 GB download, 40 GB uncompressed - a version with high resolution textures in critical areas around bases, etc. This is the size of the largest current PC games like Titanfall. It is also a size that one might be able to fit on a current SSD for fast loading. This version could also be put on 1 single layer Bluray and shipped to people - Bluray data drives are relatively inexpensive now.
-100GB+ - the "insane version", shipped on multiple dual-layer blurays OR a hard drive.
Since I have only tried the lowest resolution textures in the new 2015 Beta, it's not clear to me what the performance impact of running 100s of GB of textures would be when running off a HDD.
I do have space in my PC setup on a RAIDZ2 NAS attached over Gigabit ethernet, spinning HDDs, and SSDs, so if I could get ahold of a copy of the new "insane" textures I would be more than happy to benchmark the 3 use cases for comparison.