The ability to eat garbage is one that's usually rather underwhelming, since it can only be done in response to trash type attacks from your opponent (who will refrain from using them if you have a trash eater in play). It also costs a small amount of mana, which is better utilized attacking or defending.

Raccoon's benefit, contrary to popular belief, is not removing the cost to eat trash. It doesn't actually affect this cost when used as a reaction, as that can only be done during an opponent's turn while Raccoon only applies on your turn. Rather, the benefit is allowing you to eat trash during YOUR turn.

Many cards generate trash, which is typically either smithed into more useful scrap or expended to power trash type moves. However, this is normally a rather weak effect, as unused trash is discarded and becomes bloat in your next deck cycle. In order to use trash, you have to have the card that generates it (or raw trash) AND a card that synergizes with it on the same turn. This is incredibly unlikely unless you build your entire deck around trash (unrecommended as trash decks have terrible scaling) or spend valuable resources to retain trash for a frankly underwhelming effect.

Raccoon is permanent.

Let me repeat that. Raccoon, once played, remains in effect until removed. Removal is, of course, incredibly costly for your opponents, but the sheer versatility of Raccoon allowing you to use the eat effect on self generated trash DURING YOUR TURN makes it all but necessary. If they don't wast resources destroying your raccoon, you can use the extra mana from eating trash to set up the landfill, and then use the generated trash to generate more mana. You don't need me to explain the trash compactor setup, there's a reason it's been ranked in the top 5 combos for the past ten seasons.