Last time they can easily offer 100gb free as marketing gimmick because they know average user can only use so much.

Now 100gb usage on average user is totally on realm possibility. Imagine each of those 3.5inch HDD in their DC, typically 8TB - could only hold 80 users if everyone actually use their 100gb allocation. Now make it 3 x8gb HDD for let say, parity and backup. And now put the total gsuite users into the equation. And then you calculate all the energy costs to drive all those drives. Shit got ugly real fast.

people tend to think cloud storage is some kind technology magic that just dump your files into endless void. Not many of them stop to think that those data still has to go somewhere. And it is stored in none other than the very same hdd your have inside your PC.