I feel like outright creating your starting mercenaries puts too much focus on them in a game with such high lethality. Kind of like how you don’t choose the looks of your troops in the original x-com. In most RPGs you’re going to spend a lot of time looking at your initial character because you as the player are meant to identify with them, so having them be customisable makes sense. In this game there’s a good chance of all of your starting members dying, so having the start of the game give them a disproportionate amount of attention feels wrong. The banner and name of your company should be more important to its identity than which mercenaries you start with. It also clashes with the atmosphere that the game currently has where all the game elements are abstractions of what feel like ‘real’ actions. Outright creating characters clashes with this.
I really don’t think it’s a huge balance issue to let you specify your first 3 brethren. They are, after all, only 3 people, out of the 12 you will be fielding.
Also, if you’re using This War of Mine as an example, the players that want to start with two old teachers for the challenge can choose to do so, and the ones that want to start with a scavenger, a trader, and a cook for easytimes have that option as well.
It’s the gear that feels like the biggest unbalancing factor. Take that away and it’s much less of an issue. I also like the idea of ‘buying’ your starting characters, though I’m rather enjoying the completely random start that the game has right now.