If they added more commanders to those you could bring with you into battle, it would make the decision less significant. Same goes for if you could change your commander once you have chosen it, why not just make all the units available and get rid of commanders all together? I think the limited commanders that you can bring into battle and the permanency of the choice once made gives that "key choice" to the gameplay as well as a risk/reward for particular strategies. That being said, I do think a confirmation window is a good idea.
Well, no because these key choices aren't being made in a matchup. The choices of which commanders (or bulletins) to use are chosen out of game, and cannot be changed in a match-up. It's not a strategic decision so much as a strategic restriction. Not to mention, a major aspect of gameplay (which is strategic choices) are being made before a match even begins. I've on a number of occasions forgot to change loadouts between a 1v1 and a 3v3 so I was completely screwed with my strategic choices because some commanders are just not feasible by themselves across multiple maps or game modes. In fact, just the map itself has a major impact over which commanders are useful or needlessly gimped.
A commander with air support is much less effective on a map with blizzards because the planes are disabled for half the game. An urban map more often than not makes ISU-152 and Elefant commanders a strategic blunder. Just having one of those commanders on the loadout can be crippling to your ingame tactical options, and we can't exactly predict exactly which map we're going to be playing, even though we can veto some choices. (I usually enable 4v4s just to disable all the 1v1 maps I can't stand, so if I am going to play 1v1 it's only going to be on a couple maps.
You're not picking your strategies, you're picking your restrictions with commander loadouts. It's similar, but not the same. The fact that there are getting to be so many different commanders is going to make CoH2 more and more of a challenge to keep in balance, especially since people have paid money for them.
On one hand, a ton of the commanders are basically clones of each other with a few swapped or exchanged abilities, leading to more or less redundant choices. Which makes balancing easier because there only a couple of viable choices: a change to smoke canisters or PPSH upgrades affects a bunch of commanders across the board. It's all very redundant and despite the number of commanders they function in only a few limited ways. Being able to choose from one of 5-6 commanders is meaningless because there's very little variation between them all. Especially considering generally only 1-3 of any commanders abilities are ever used to any strategic significance. They're all pretty one dimensional until...
You look at the other hand, with a growing number of commanders that introduce a slew of new units and abilities otherwise unavailable to players, this model for easy balancing and strategic choice is quickly undermined. FHQs and light ATGs, repair stations, tank traps, booby traps, soviet heavy tanks, assault grens, ostruppen, trenches, and so on, all are radically different from the rank and file of (free) commanders. These are all great packages of interesting new strategic content... But they come at the cost of existing strategies.
It's not exactly easy to change and balance things people have paid money for, and so without a meaningful way to integrate these commanders, it's just going to slowly turn into unbalanceable bloat. And because the most innovative and novel additions are being introduced from behind a payment barrier, (I'm referencing the Case Blue releases, not so much Turning Point.) none of these features can necessarily be implemented to the greater game without directly undermining sales. You can't have people paying for the ability to choose assault grenadiers, then provide them in a free commander at a later date, for example.
The only thing that influences commanders after selection and choice is the amount of CPs a player has. If CPs had to be first allocated, and also across at least more than one linear path, (even if it's choosing one commander, and then sacking it for another) then there would be a level of strategic depth beyond initial choice. Spreading out CPs too thin would cripple any player lategame, as lategame units require investing heavily down one path. In vCoH each of the three doctrines had two paths you could choose to go down as you allocated CPs. You could choose one doctrine, but the decisions to go down the left or right side of the tree or split CPs across each had HUGE impacts on what the player could do. So for example with the American infantry doctrine, allocating 3 CPs meant getting Rangers (elite infantry squad with bazookas) or having an offmap artillery shoot.
Choosing wrong allocations could certainly cost you the game, which was great because actual gameplay would influence those decisions. The infantry doctrine could result in overwhelming artillery support, or overwhelming unit fielding (offmap combat group ftw) but rarely both until the extreme lategame. But choosing the doctrine didn't force a linear path of gameplay for the player, and that's an important thing to keep in mind as far as strategy is concerned.