Usually, this two-mana creature goes into decks where most of the cards dont cost that much mana, and where the benefit of having an extra card each turn outweighs the downside of losing life
As anyone who has played Magic for any length of time will tell you, casting spells for free is, more often than not, quite good
Lands (16) Spells (44) 4 Brainstorm 4 Vampiric Tutor 1 Mystical Tutor 2 Yawgmoth's Will 4 Mana Vault 4 Dark Ritual 1 Megrim 4 Memory Jar 4 Defense Grid 4 Tinker 4 Mox Diamond 4 Lotus Petal 4 Lion's Eye Diamond Sideboard Like all of the most broken decks in Magic history, it featured two Yawgmoths Wills, because there was plenty of time to find one you know, later in your first turn
Turn 1 Serra Ascendant is a powerful play, a Flying 6/6 with Lifelink
Tide Skimmer's ability triggers just once, no matter how many creatures with flying attack beyond the second