A useful card for its color can be considered one of the best
By the way, I don't know if you noticed, but the modern Oracle wordings for the ten dual lands has what they tap for in reminder text, so they are, technically, according to the same wording as Urborg, Tomb of Yawgmoth, now fully colorless
But the sub-game that naturally evolves from their first activation feels more interesting, and far less overwhelming to opponents when theyre accelerated out on turn two or three
But neither is required for the decks to work
Since Mirri, Weatherlight Duelist has first strike, you dont have to worry as much about attacking with it to benefit from its abilities