I'm not saying you're wrong, but what I think Pep has a preference for. When you play a 4231 and have 1 playmaker, although you have a more solid midfield, it's easier for the opposition to mark the #10 with their DM. Having 2 creates more problems for the opposition with overloads on both side. The width of the wingers create space for them in the middle as well.
Going 3 at the back means more crosses from the wingbacks and being direct like you said, but we don't have a big striker in the middle. You can play 3-5-2, but that means 1 of your wingers will have to go in Mahrez or Sterling (although he's out of form). I don't think Pep would play a 3-4-3 because he likes to have control of the midfield. Usually he's had KDB drop deeper in a double pivot where you'd want him further up the pitch.
Again this is by going what I feel Pep believes and with a fully fit back line I do think these are some of the reasons he likes the 4-3-3. But this is the Skriniar thread so apologies.