Sigh
Ok, let's pretend for just one moment that we don't have actual proof of the effects that stating out every monster has on actual game play. Let's assume that we haven't seen how much longer and more complicated things get when you have to figure out all the little bonuses and track a ton of stuff for something that's only going to be alive for a few minutes. Try to forget all the endless hours of prep that were necessary to prepare for a 3.x adventure.
Let's just answer the question, why don't monsters have a strength bonus.
So this argument is from realism, right? The players are swinging a sword and Harthgar Snigglepants the dwarf does a minimum of 3 damage, so how come a monster can end up only doing one? It doesn't make sense. It isn't realistic.
Well, that's not the intent.
Generally without strength, monsters are designed with more attacks and larger damage ranges than players. Olden times, you would see an entry that would say 2-8 or by weapon type (as gnoll), or perhaps you might find another entry saying 1-12 damage (as mummy). What are these creatures attacking you with? A slam? Their claws?
You know how much you do with your fists? One point of damage.
The second and more important point, is that these are monsters fighting the heroes. In mighty tales the monster often makes a vicious attack and due to the fortitude, luck, skill, and majesty of the heroes only does a light scratch.
The damage isn't supposed to be some realistic physics model of damage, it's supposed to abstractly represent the tales of heroism from youth.
So stop worrying about trying to get monsters to work realistically and start having more fun.
