11% still play HD2 with a spinning drive? I would've never guessed that. There's probably some vicious circle thing going on: because the install size is so big, people need to install it on their secondary, spinning drive...
Because it's a recent 20TB HDD the read speeds approach 250MB/s and I've also specifically partitioned it at the beginning of the disk just for games so that it can sustain full transfer speeds without files falling into the slower tracks, the rest of the disk is then partitioned for media files that won't care much for the speed loss. It's honestly fine for the vast majority of games.
Yes, because they apparently still duplicate data so that the terrible IOPS of spinning disks does not factor as much. You people need to stop with this so that we can all have smaller games again! ;-) <--- (IT'S A JOKE)
SSD sizes are still only equal to the HDD sizes available and common in 2010 (a couple TB~). SSD size increases (availability+price decreases) for consumers form factors have entirely stopped. There is no more progress for SSD because quad level cells are as far as the charge trap tech can be pushed and most people no longer own computers. They have tablets or phones or if they have a laptop it has 256GB of storage and everything is done in the cloud or with an octopus of (small) externals.
Sure, there is some limitation in format, can only shove so many chips on M.2, but you can get U.2 ones that are bigger than biggest HDD (tho price is pretty eye-watering)
I think this is more a symptom of data bloat decelerating than anything else. Consumers just don't have TBs of data. The biggest files most consumers have will be photos and videos that largely live on their phones anyway. Gaming is relatively niche and there just isn't that much demand for huge capacity there, either -- it's relatively easy to live with only ~8 100GB games installed at the same time. Local storage is just acting as a cache in front of Steam, and modern internet connections are fast enough that downloading 100GB isn't that slow (~14 minutes at gigabit speeds).
So when consumers don't have (much) more data on their PCs than they had in 2015, why would they buy any bigger devices than 2015? Instead, as sibling commenter has pointed out, prices have improved dramatically, and device performance has also improved quite a bit.
(But it's also true that the absolute maximum sized devices available are significantly larger than 2015, contradicting your initial claim.)
You can buy 16-32TB consumer SSDs on NewEgg today. Or 8TB in M.2 form factor. In 2015, the largest M.2 SSDs were like 1TB. That's merely a decade. At a decade "plus," SSDs were tiny as recently as 15 years ago.
[1] https://www.microcenter.com/product/659879/inland-platinum-1...
[2] https://www.microcenter.com/product/700777/inland-platinum-8...
(More relevant might be that backups are a largely sequential workload and HDDs are still marginally cheaper per TB than QLC flash.)
Tape, M-DISC, microfilm, and etched quartz are the only modern mediums that are meant to be left in storage without needing to be babysit, in climate controlled warehousing at least.
Edit: Forgot it was released recently on Xbox Series consoles but those also have SSDs.