We'll get to that soon, though
Using mana rocks like Sol Ring or Arcane Signet to accelerate your mana production so you can cast your spells more efficiently
This allows us to revive a Basic Pokmon that was defeated in battle, though not directly, and bring it back into play
When a cards primary function is to accelerate you, the difference between a one-cost card and a two-cost card can be a lot, and when its a creature with summoning sickness, the difference is felt even stronger
The final point is, according to Blake Rasmussen, exactly why Common cards are still present in Collector Booster packs
Tigra, Feline Fury would fit best in a green-based lifegain or +1/+1 counter deck, especially in Commander where repeatable life gain (Soul Wardenstyle effects, lifelink creatures, or cards like Wellwisher, Prosperous Innkeeper, or Heliod, Sun-Crowned) can quickly stack counters and turn Tigra into a large trampling threat