>>96250240
It's mainly because rotation just happened and the main people playing standard right now are either people that are running rotation-proof decks with some of their rotated removal swapped out and people trying to find ways to keep playing their pre-rotation archetypes (mainly Overlord and mice/RDW). Once people start actually playing around with the new cards, we'll start seeing some diversity in the format.

Will it last? Depends on how well it handles UR Cauldron and UB midrange. All I can say for sure is that a lot of people seem to be underestimating how good the monogreen cards in this set are. It definitely seems like play design really were trying to push a lot of monogreen aggro cards in this set like they said they were. I'm almost certain we'll eventually start seeing more people with decks running either the 1-mana green Zada or better Springleaf Drum on a robot insect body.