I feel, this evasion criterion is really niche. Often damage before combat just removes the blocker entirely.

And I don't see this as something particularly related to this set. Am I missing something?

It's niche, but cards in set do offer support Lava Catapult and Flameblast Duelist, and possibly (but perhaps not probably) Engineer Archmage, Shocking Jolt, and Warforge Foundry.

The evasion was a top-down flavor addition, although that may not be clear without flavor text. The idea was that the weight of the morning star is enough that it would crush anyone already injured.