Well... You don't really need armies of peasants and SS. While they do have lower stats than gals, some of those stats can be trained to the same level as gals can. Accuracy, throwing etc.
The best use of them is of course tanks. Gnomes are fairly hard to get, while tanks can be rushed in research, so they are usefull.
There is also a couple of missions that gals can't go, so this is also something to keep in mind.
Right now I will always go for the "Male Touch" route, thanks to the gameplay becoming more of a challenge without adding more enemies, or increasing their armor. It's at this point that you start to love mortar (that feeling when you bomb Church Boot Camp, killing everyone in second turn is just... Nice). Where Gals are rather generalist and can do everything good, you have to play differently with others.
Lokk'Nars are snipers, or poison dagger silent killers. SS are the main meat that just fights. Peasants start as rather support unit for healing and such.
Gals at this point become Heavy Support and Melee specialists.
And I don't think Expeditions are too powerfull. Lack of cover on the first turn increases risk and with low HP Peasants/SS/Lokk'Nars it's a significant risk. Trucks do way better.
Hmm - you are right I should consider replaying with male soldiers...