This is especially true against Prowess and Landfall decks, as the combined bounce and removal effects set them back massively
Tapping two gives you a mana of any color
Or perhaps not
Another very important thing to note on Merlin Squirrel/Rabbit/Crab/Goat is that they say, when he leaves play, meaning its triggered whether the card is returned to your hand, banished, sent to your ink well, or even shuffled back into your deck
Sure, half of them will die at the end of your turn, but the tokens they generate still stick around to attack the turn after
2 Aragorn, The Uniter Heir Of Isildur Returns Playing four colors opens up a wider range of options to you, and playing Aragorn, the Uniter, you are setting yourself up for an extremely rewarding scenario