I would submit the root cause of this is not what you might expect. I would say it's a failure to understand that "everything is correlated":
https://gwern.net/everythingWhat I mean in this case is that if you say to yourself, "hey, only 4% of my users are using more than 50 gigabytes, and I can afford to lose them", it is very likely you are using a model where those 4% of your users are essentially uniformly randomly chosen from your user base. You can see usage, and you may not be able to see much else, so you assume that usage is uncorrelated to any of the other aspects of these users that you may care about.
In reality, everything is correlated to everything, and what that means in this case is that your 4% of users are not being randomly chosen from your user base. This doesn't mean that every way this sample deviates from random is bad for you; you certainly can just get lucky. For instance, that 4% of users probably includes a huge proportion of your users using it for piracy or similar activities. Cool. You may even be using this as a motivation for the action since you can see this to some extent based on reports and analytics, certainly.
Unfortunately, that 4% probably also includes a disproportionate number of your True Fans, who love Google partially because of this free drive space, and because of that love, drove their work environments to Google Teams and other paid services, thus netting Google profit far beyond the costs of this particular Drive account, but indirectly and where accounting can't see it. True Fans who will perceive this not as a business transaction, but as a betrayal, and who may in their passions take actions to do things like (on the margin) remove their companies from paid Google services, and take time out of their day to create bad press.
I'd say that's the core mistake being made over and over. You think you're just getting rid of your "problem children" but those problem children very frequently have correlations to something you do in fact actually want.
Of course, that doesn't mean you want to be abused either. It just means a more delicate approach may be called for than just hacking off a chunk of your user base when you don't really know what it contains. It ought to be an assumption that any time you're taking an even slightly non-random slice of your user base like this that it may have hidden correlations in it you're not taking account of.