One of the first pieces of advice given to me was to make squads my first military tech and i know a lot of others play the game this way. And to my mind, there should be no such thing a necesarry choice in this kind of game. If we can't make it non-necesarry, we can at least make it automatic.
Advantages of making all recruitable units groups of 3 by default:
1 It will increase the "epic" feel and look of the game
2 it will reduce randomness as we will always be dealing with larger numbers of hp
3 it will stop the ai recruiting small, pathetic units. this will make settlements always better defended, since the default unit strength will be higher
4 for the same reason. it will make battles faster as you will generally have fewer units moving and attacking all at one, so you don't end up watching the ai move 10 soldiers all individually in the midgame (i have personally never seen the ai field a squad, but i have never played any really long games). this will also leave more space on the battle map for maneuvering.
5 it will reduce the importance of the warfare tree in comparison with others by removing one "essential" tech to be researched
6 it will make sovs/heroes seem more heroic as they will be a completely different type of unit. yes, they will need to be rebalanced to be competetive vs. groups, but to be honest, this needs to be done anyway.
this is not to say that the larger unit techs whould not be researchable, just that you should start off with groups of three of everything except pioneers.
i will admit, i just came up with this and it may be completely underthought.