It absolutely should NOT be Overwhelming Forces. The Oracle text for OF is target opponent, not all opponents, and in a format geared towards multiplayer it’s an underwhelming wrath for the CMC.
It's not underwhelming at all, it's a much more political spell, if anything, you target the token player that made an army so that azami wizard tribal is not forced to counter your removal spell because would damage also him and also leaves your army unharmed. It's VERY much a commander suited card, it's just not as brainless as Decree but you actually need to be much more strategical for optimal uses. Also did you realize that Forces ALSO like Decree makes you a ton of direct card advantage and doesnt just removal? 8 cmc it's a super fair cost for the potential effects.
yes I know this should have been Overwhelming Forces but Decree is strictly better
As usual people abuse of the word "strictly" better on cases that aren't strictly better at all. Decree destroys also your creatures, Forces leaves your army unharmed, and if you got a big army and get rid of the defense of the army of another player, well guess what, it's likely you kill him on the spot. Not strictly better like, at all, just for different uses and different decks and strategies.