Standard is competitive, and bad decks don't do well.

The deciding factor of whether your deck does well has nothing to do with how fun it is. It's based on how good it is

If you're concerned about winning, you should play a good deck. If you don't care about winning, and just want to have fun in some other way, then why does it matter if your fun deck doesn't do well?

Ultimately, you're playing a 1v1 adversarial online multiplayer game with matchmaking. What would arena look like if bad decks did just as well as good ones? Magic would have to be a non-skill-based game. Or you would have to infringe on the rights of the players on some way to stop them from playing effectively.