I disagree that this is a cost-saving fad from big-money publishers, or even a fad at all. It was very common if not the norm for many years across many genres, especially when storage space for frivolous text was severely limited, and digitized speech was an expensive novelty that sounded terrible anyway. Over the years, text became trivial to include, while voice acting is still expensive. If anything, protagonists that speak have become more common since the early days, not less, especially in games that aren't fully voiced. There's no real financial incentive not to write some plain text; it's done for stylistic reasons. Meanwhile, in fully-voiced games, you may have the budget to voice, say, 500 lines of dialogue; the pressure here is to keep the total script to 500 lines, not to silence the protagonist specifically. At most, doing so might be marginally convenient. It certainly isn't a bullet point feature to boost sales.
I don't see any evidence that there has been a large-scale shift in the industry towards protagonists who should speak no longer doing so. That's a very strange claim to make.