Its been a cornerstone of archetypes, such as Gardevoir ex, Lost Box, Raging Bolt-Ogerpon ex, and others
This card also became my friends avatar on Discord for a long time, so it holds a special place in my heart for that alone
Lee is curator of nostalgia and a long-time collector of loveable junk
Compare that to something like [card]Serra Ascendant[/card], which enters the battlefield as a 6/6 creature with lifelink for just one white mana, and its easy to see why that card is a format staple
And if its later and you want to trade the attacking 3/3 for a nasty creature, knowing that the Champion is likely to be blocked and die, well, that was using it just like a four-mana sorcery that reads, Put a creature from your hand onto the battlefield. And dont forget the potential reusability of the Champions exert later, as well as Greens acceleration getting the Champion out and swinging earlier than its 4th turn sell-by date the other colors 4-drops would normally have