It can be a big deal even in blue decks, spreading out the cost of your effects between your colours (assuming you are fairly even split already) typically makes your life a lot easier
You might not get the absolute head-knocking power of Doran, the Siege TowerDoran, the Siege Tower, or the powerful recursion of Colfenor, the Last YewColfenor, the Last Yew, but what FangornFangorn does provide is the slow, plodding advancement of your board through mana advantage and constant attacks turn after turn
The game was designed with players completely new to the card game in mind, and that philosophy is reflected in the card pools themselves
A card priced at $200 with historical weight (like the full Pikachu V-UNION set) ranks above a $400 card from a generic set because collectors hold the former longer and pay more for graded copies
That and the land comes into play untapped, so it's essentially Rampant Growth for less mana