Arena echoes are the least interesting, least fun, and most tedious of all echo types, by miles. They should be relegated to the ladder.
This is made worse by the fact that you cannot reroll them the way you can reroll any other echo objective. If you hate Spires, and you end up with a Spire map, you can just port out of the echo immediately, and when you re-enter it a new objective will have been rolled.