In other words FB saying we are going to now start providing you with X services and you are going to give us Y data.
Sure the user might benefit from X, obviously even that could be argued, but the idea is this isn’t a bargained for exchange/negotiation. This is unilateral modification without consideration, it’s not enough for FB to say they modified the data collection/rights which is justified because FB also changed the service.
That’s like saying you ordered a cheese pizza for $10, the company unilaterally charges you for $1,000 and justifies that because they bring you 100 pizzas...at no point was there consideration for the modification of the agreement even though you got 100 pizzas. Similarly can FB just start collecting more data/selling to third parties by unilaterally changing their terms and justify it by saying a unilateral change in service equals legal consideration?