For decks that can abuse the mana upgrade in one turn, this is plenty good enough, hence the card remaining on the Legacy banlist and Vintage restricted list
This can avoid a lot of headache and potential grievances on the table, and you really want to maintain friendships over the fleeting satisfaction of winning
If that player is an opponent, The Heron Moon's ability will trigger that many times
In other words, because youre going to see lots of cards and be able to grab Birds from among them, having nice utility birds like the Keeper is nice
That is what allows it to be a commander after all, as clarified by Wizards of the Coast in a rulings update
Often I find that when I need them or theyd be useful I dont have them, and when I have them Ive nothing to use them on