I don't actually think so.
1) The difference in cost between $2 and $4 is actually huge. You can pick up $2s with spare midgame buys if you're building an engine much easier than $4s.
2) Scout doesn't draw a card. So if done wrong, the scout actually *hurts* you unless you see a victory card. A hand with a bunch of Pearl Divers and no mystic - well, you just play them as cantrips, they didn't hurt you. A hand with a bunch of scouts and no mystic? Not so good.