Haven isn't for money smoothing, it's for action smoothing.
As to markusin's objection that you rarely have an unplayed action to put back, I'd say that there are a number of scenarios where that isn't uncommon.
- Gainers may cause you to be flooded with Villages, if the terminal draw is at a price point > $4.
- Your deck may be really big, with a sizable amount of junk still left. In these cases you often want more engine pieces than the bare minimum needed to achieve your goal for each turn, just for consistency.
- Your deck composition may be rapidly changing in a way that leads you to have a little extra draw. Two examples: you finally acquire and play a Forge on a big hand, you use Altar to replace junk cards with Stables/Lab/Hunting Party/Whatever. In general, slower trashing can lead to this situation.
- Handsize attacks are a big case, it can be useful to overbuild draw in these cases to fight the attack and, even more importantly, deny draw resources to your opponent.
Anyway, Haven still isn't that great, but it can still be relevant on a decent number of boards.