Since posting about this I've been observing more closely how this would work. Here's some of what I've noticed.
Firstly, I'll preface that there are basically two kinds of games that end by 3-pile rule, ones that end very fast (what I'm critical of) and one's that take a significant length of time yet end by 3-pile rule (what I'm not critical of).
I've noticed that in 3-pile rule games that take a significant length of time, often at time of ending there will be a fourth pile that is very close, at something like 2 cards left. These games will take only 2-4 turns longer as 4-pile games than they would have taken as 3-pile games. I gotta say to the people gushing about the deep strategy of 3-pile endings, that as a 4-pile game these game will have just the same amount of strategy involved. Maybe after more observing of specifically the games which went pretty long but ended by 3-pile, I can come up with a percentage that had a fourth pile which was also close, but so far it feels like roughly 60-80%.
On the flip side, when you look games that end very fast by the 3-pile rule (think things like cultist, magpie, or any number of things depending on number of players and how they like they to play) these games are made dramatically better when played as 4-pile. When you look at games on the short end of the spectrum, there's no denying that extending the length shortest games by 15-25 turns would add a ton of strategy to games that had a disappointing lack of it.