How bad is Holy Wrath?!
It's bad, but not that bad. In a typical arena deck, it's on average a little more damage than Hammer for 1 mana more, which is definitely not something you prefer, but it's playable since at least it's a cantrip, if an expensive one. It's much better in high curve decks. People play it in constructed giants Paladin. Drawing Molten Giant with it is amazing.
He just really, really suffers from the fact that he's a 5/3 for 6, and trades with a lot of 2 drops.
It's not just this. It's the fact that it requires a combo. If it didn't require the combo, it might be playable. But as is, you can't really play it until like turn 8 or something.
Thalnos and (for Miracle Rogue) Edwin increase the deck strength a lot, but you can get by without them.
I'm currently running a variant of Miracle that I call "Midrange Miracle". I've removed the weaker spells like Shiv and third AoE spell, and cheaper minions like Thalnos, Edwin, Coldlight/Acolyte/Hoarder; and I've replaced them with solid normal midrange minions including 2x Farseer, 2x Teacher, 2x Azure Drake.
This makes it a little harder to churn through the deck, but it has enough positive benefits to more than offset that.
1. It allows you to do more damage in the midgame, so you don't need a full double-Shadowstep combo. Usually one Shaodwstep is enough. You can even win without Leeroy by using Cold Blood + Conceal with multiple minions on board.
2. It makes it easier to keep up in the early and midgame, so you don't have to spend your turns just playing hero power and Shiv while your opponent builds his board. In particular, the Warrior matchup is usually bad for standard Miracle Rogue, but if you're playing reasonable minions, your opponent has to take some damage axing them and won't have all the spare mana to armor up every turn to get out of burst kill range.
3. The midgame minions may draw some removal, which leaves less for your Auctioneer.