For 1R, you can get two goblin tokens (Dragon Fodder). For 1RR, you can get three goblin tokens (Hordeling Outburst). So why does 3.5 goblin tokens cost 4RR (Box of Free-Range Goblins)?

For the potential of getting up to six (and maybe even more if you’re also playing black) and the hand dandy Goblin Explosioneers watermark. : ) The more serious answer is that effects are costed for the environment they are in and not necessarily against every other card that has ever done the effect.

With regards to what was asked about an anti-invasion (non-creatures only), couldn't creature token sources just have a way higher frequency in that set/block to compensate for the lack of creatures​ in the set/block? (i.e stuff like dragon fodder or dance with devils)

Imagine the battlefield full of pennies or glass beads, representing a variety of different sized creatures. You think to yourself, “If only there was a way to represent the size and ability of each creature to make gameplay easier.” : )Either you’re playing the game with nothing but vanilla creatures, which would present numerous issues both from a functionality and gameplay standpoint, or you’re making more complex creature tokens at which point you should just be making creature cards.

Un-Rules question: When Meddling Kids refers to a card's "text box", what part of the card is that? If I choose the word "Goblin", my opponent can't cast Dragon Fodder, but can they cast Goblin Game? What about Ankle Shanker?

The text box is where the rules text, reminder text and flavor text reside. Meddling Kids do not affect a card’s title, mana cost, card type line, power/toughness or any legal text/collector number info.

Is it possible for Green to get a token making instant like Dragon Fodder or Raise the Alarm, but making elves instead of goblins or soldiers?

We’ve moved away from Green making small tokens as a single effect so while possible it’s unlikely.

Isn't Dragon Fodder from Jund? What's it doing in Origins? It could have at least had new art/flavor to fit it into, say, Regatha.

We counted Alara as one of the ten planes and allowed art from any of the five shards even though Gideon only visits Bant.

Why does Krenko's Command exist if we already have Dragon Fodder? They're the same card, except for the name. Is it just for flavor, or is it to allow players to put four of each in their decks? On that note, why do both Terramorphic Expanse and Evolving Wilds exist? Is it for the same reason?

We change names for three basic reasons: 1) The old name doesn’t fit for flavor reasons. 2) The new name is trying to play up something important with flavor. 3) We want to let you play with eight copies of the card. Krenko’s Command is #2. Evolving Wilds is #3.