Maybe it has something to do with the sentiment that "if it's free, the product is you". Perhaps without paying some form of subscription, you feel that there is no 'bounded' payment for the service - as you consume more of any given service, you are essentially paying more (in cognitive load or something similar?).
Kind of feels like fixed vs variable costs - often you feel a lot better with fixed as it tends to be "more valuable" the more you consume.
Just an off-the-cuff take based on personal experience, definitely interested in hearing other takes.
In light of reading through Raemon's shortform feed, I'm making my own. Here will be smaller ideas that are on my mind.