The Merchant Affinity Action in the Classical Era offers you these exchange rates:

1. Invest in a luxury resource owned by another player and get 100 Money at a price of 70 Influence.  (a nearly 1:1 trade of influence for Money is terrible)
2. Build an extractor in a territory you own for 70 Influence.  But note that building that same extractor can be done at any time, outside of this mechanic, by spending only 44 influence.  Virtually half the cost.  Using the affinity action costs you nearly double.

Perhaps this gets better in later eras, but why would you ever use this affinity action in the Classical Era?

The game calls the Merchant Affinity Action "Power Investor," but surely that's a misnomer.

Agreed, the Aesthete Active ability still seems a bit overtuned, and now the Merchant ability is a little undertuned.  Maybe it's a side effect of a resource being traded fewer times (the money granted by the ability is related to how many buyers there are for the item) or maybe the number has changed.  Regardless, it's not really useful for boosting your money, but it's still useful to build an extractor in a territory the owner won't, so you can then buy it.

Agreed, Arachnodord, the new Merchant passive ability to buy trade without treaties is wonderful, especially as you've said in the later eras.  Being a Merchant in the early eras — Nubians, Phoenecians, Aksumites, etc. still pays off because you'll have a strong foundation of money to pay for those trade routes later on, and unbonuded access to the world's resources really pays off for Era III-V Mechants.