I mean, anyone can ask for an objectively flawed product, it wont change the fact that everyone and Larian will laugh at the suggestion.
balancing in a single player experience (or even coop) like the BG games is largely an effort in futility. Given the number of variables, party composition, choice of classes, spells, feats, etc... skill at using those spells and abilities, even the penchant for farming, mean that any meaningful balancing exercise is very unlikely to be successful. The best the game designers can hope for is to make sure it isn't overly broken one way or the other.
And with it being single player (or coop), balancing isn't largely needed. Yes, you want to make it challenging enough that the average player isn't bored or frustrate. But beyond that, it is just an exercise. PLAYERS will compare their 'skill and prowess' against each other. But the developers are mainly hoping to make a fun and interesting product, not something that is used as a benchmark for skill.
I am not saying that balance isn't a factor when considering party size. Just that what has been seen thus far in the beta, the current game composition (vis a vis balancing) nothing precludes them increasing the size of the party. Simply that it hasn't been seen in the current build. Anyone waving their hands saying "It hasn't been tested, means it isn't being considered" is simply speaking their preference in the hopes it is fact.
