I have one last argument why I don't like promo cards. I know the promo cards but I can't/won't play them. Later on, when they are released, I'm not excited for them anymore because I know the card already. even though it's a new card. This happened with Ballista, messenger of Bim Shalla, temple high guard, ...
Getting off topic, but for our regularly scheduled organized play, I allow myself to include at most 1 copy of 1 promo in each of my books, and I'm fine with opponents using promos to a reasonable extent. That said, if you're spamming a promo that's known to be really good, like 4x Ballista prior to it's errata/release, or to 4x Acid Blast, etc, then I might take some exception, but having 1 or 2 promos for flavour and/or variety is OK. Nobody's going to get upset if you played an Unstable Fire Imp or Eeker or a Screaming Zombie or a Blur or even a Sherean Leviathan or Victorian Griffin. And I may or may not choose to play my 1 copy depending (a) if a situation warrants it and (b) if my opponent is OK with it. If not, it's dead sbp's in my book, so it's to my disadvantage.
But yeah, Fire Elemental and Magma Golem may have actually lost their lustre since being printed in Lost Grimoire. If they hadn't been printed as promos, everybody would be going "WHOA!!! LOOK AT THAT! AMAZING!!" but instead it's more like "Oh, they finally printed that in a set. Too bad the Wizard isn't trained in that school anymore, and that a similarly powered Demon is generally better for either of the Warlocks..."
That said, I'm tempted to try the Magma Golem as a buddy for the AT Warlord. It's only 6 sbp for a Warlord (e.g. level 2 Fire and level 2 Earth), same as it would have been for a Fire or Earth Wizard, and same as for a Warlock.