As I keep saying, what I don't think realize is the way in which stewardship bonuses scale because of the demesne limit increase AND tax increase. Let's do some quick math here: Let's say you get 1 extra county per 10 stewardship (old numbers). Assuming each county only has a single castle with an income of 4, let's take a King with no legalism.
A King with 0 self+wife stewardship would get 4 counties * 4 income = 16 gold a year
A King with 10 self+wife would get 5 * 4 * 1.20 = 24 gold a year. Note how income has jumped 50% with only 10 stewardship difference.
A King with 20 self+wife would get 6 * 4 * 1.40 = 33 gold a year. We're now making more than double the amount of money as a 0 stewardship ruler.
A King with 30 self+wife would get 7 * 4 * 1.60 = 44 gold a year, almost triple the income of 0 stewardship and almost double the income of 10 stewardship.
This isn't accounting your steward's stewardship. Let's assume we have a 15 skill steward (not hard to get). The numbers are now:
0 self+wife = 21 a year
10 self+wife = 30 a year
20 self+wife = 41 a year
30 self+wife = 56 a year
That's the raw demesne income. Of course this doesn't account for the fact that each castle also gives you hundreds of extra troops, or that each county gives you additional cities and temples that even further raise your income. So we're talking about getting triple the income, at least 1000 extra demense troops AND more city/temple vassals for going all out stewardship... and that's with numbers significantly nerfed from vanilla.
In short, anyone who thinks stewardship has been nerfed to uselessness is plain wrong. It just happens to be insanely, insanely, INSANELY overpowered in vanilla to the point where even a large nerf is not enough to bring it on par with the other stats.