Allow me to clarify my point/reasoning:
1. To cater to the "console crowd" - i.e. a control scheme that isn't suitable for handling a large force, a modern-day view of difficulty/frustration/time consumption in gaming, and *cough*shortattentionspans*cough* demand for fast, action-oriented gameplay - the game will be balanced around small squads and low lethality, at least on Normal Difficulty.
2. The devs, however, are aware of the appeal of high lethality, "squaddie of the week" gameplay, and want to cater to that crowd as well.
3. Thus the 'Classic Mode' difficulty level, which will be more lethal, and either enable bigger squads in the vanilla game itself, or will (hopefully) be easily moddable for that end. I'm guessing the "PC" interface (which may or may not be PC exclusive, this is irrelevant) will facilitate management of a larger force, compared to the standard "console" interface (where it seems you have to sequentially cycle through the squad to select troops, at least judging from the screenshots).
Maybe I'm reading too much into it, but that is at least what I'm hoping for (either that, or the whole squad size 4 issue being flat out wrong / misinterpreted).