That, and other resources tend to get compressed less as bandwidth and storage becomes cheaper overall. Less compression means less load on already underpowered console hardware and more importantly, less memory used, high end games tend to max out their IO and outright memory map things straight from the disk.
GTA V on last gen was notorious for reading off the optical disk and HDD simultaniously to spend less time moving things around in memory.
Disk failures are a major reason for performance degradation on consoles and why putting SSDs into consoles is a very good idea.
We recently started using XBox Gamepass which is a small monthly fee to get access to a fairly large variety of games (all digitally downloaded) and our bandwidth usage exploded b/c there's no extra charge to pull down 5 games that maybe looked interesting but that you would never pay full price for.
The HDD bloat really stuck out to me when I looked at the upcoming WoW Classic Requirements - the current game requires 70 GB of space, but Classic requires 5GB. All games, even old ones trying to stay modern, require a huge amount of space.
I've been thinking about this, then it dawned on me that the current live game has everything in WoW classic, and then everything in every expansion after it. The amount of video and high resolution textures in the current version of the game dwarf the original.
Happens in hardware too: the way Sony made the PS2 compatible with the previous PS ("PS 1") was simply to place an entire first ten playstation on a corner of the PCB. Cheaper and more compatible than writing an emulation mode.
I have about 150 games downloaded to my primary console. Not all of them are that big, but a good number of them are huge. Looking at my firewall logs, it's pulled down 400GB in the last 30 days. I've only installed one new game in that time. Updates for huge games can also be huge.
Also, things other than my Xbox Ones use bandwidth. They are just the largest single consumer of it.
We have 7 people in the house and I can breakdown the usage like this:
Mac sync between 5 machines (this was surprising to me)
Instagram/social(I thought YouTube would be 2nd place)
YouTube
Netflix