Part of it is resolution. The icons and such in apps are much larger now than they were in 2013. Besides that I mentioned this in another thread but rarely will a team clean up after itself. There's probably tons of dead code and what not in a lot of these larger apps. I know all the ones I've worked in had a lot of bloat just from years of work. Some feature gets added 5 years ago by a team that no longer exists, it was turned off and no longer used but who is going to remove it?

Besides that, there's just a lot of garbage that gets added by various people with different interests. An unoptimized version of the app I'm currently working on has a ~15mb binary, the core app not including all the "extras" people have asked for. It has about 75mb of assets, probably 10-15% are unused but I have no idea. The download size is about 400mb.