A post I made in my league forum yesterday seems relevant to this thread...
In my opinion merch income is one of the most overrated things in the game. My team should be about as bad as it gets, low salary, high turnover, in a relegation fight, and only one American (who is a recent purchase). I've been making a bit over 40k/week. Ignoring the Cat's NT bonus (I'll get back to it), he's making about 25k per week more than me. Let's say roughly half that is due to him having a great record and more than double my salary. That leaves only a ~13k bonus for having an American roster with multiple self drafted players. This is pennies in D2, and not nearly enough to make up for ignoring 90% of the transfer market.
The NT bonus is one of the few times when the merch bonus can be worth it, but this is only available to a small number of owners, is not that good for NT bench players, and is almost never worth it in D3 or lower due to having half your salary/value tied up in one player. Even in D2 most NT starters are too expensive to make up for the merch bonus.