I think a lot of people are missing the fact that the Resistance is not the Army of the New Republic. We don’t know what the Army of the New Republic looks like yet. The Resistance looks like a rag-tag rebel group because that’s exactly what it is.

The Resistance was established as more of a secret rebel group to oppose the growing power of the First Order. It’s not a fully-sanctioned New Republic endeavor (though they do support it in secret) for diplomatic reasons, and until the Republic is directly attacked by the First Order as we see in TFA, I feel like the Republic was officially staying out of the conflict and instead fighting a proxy war through the Resistance.

Nobody knew the First Order was as powerful as they were before now. Maybe in Episode VIII we’ll get to see the actual Army of the New Republic. Maybe they don’t have one even? Maybe they were shooting for some utopian ideal wherein armies aren’t required which necessitated the secret creation of the Resistance in order to combat threats? I dunno, that’s all speculation. All I know is that the Resistance is not the Republic.