Green Mom might feel like a 3-4 drop in aggro or a 5-6 drop in slower decks based on when you actually want to use it but because it costs one, I don't think "I would rather be playing something better" applies here because you will be playing something better, easily on the same turn. Removal usually costs more than 1cmc so he's probably good if he eats a kill spell, in fact if he's just a removal magnet, he's doing a sweet Duress impression. Also, if your deck has 27 lands and theirs has 6 kill spells, they're going to run out of removal in hand before you run out of lands to play. It might slow you down if you use it too early, but that's perfectly okay if you play any creature of the removal check variety.
Also, I want to support combo but there are so few cubeable combos in Magic that they're at a huge premium for me, I can't turn down the option to run this beautiful combo.
Also, I want to support combo but there are so few cubeable combos in Magic that they're at a huge premium for me, I can't turn down the option to run this beautiful combo.