No, increasing the tax on a region would mean that each individual would get more Lord and Knights both the differences will also be muck greater in rich cities than poor rurals.
Example:
Dantooine at 14% tax rate:
Name held by Size Population Expected Tax
Castle Dantoon Earl Suzzy 50 % 6200 154 gold |rename|
North Shores Mannor Sir Jimmy 25 % 4650 77 gold |rename|
Sea Cliff Keep (vacant) 25 % 4650 77 gold |rename|
Dantooine at 16% tax rate:
Name held by Size Population Expected Tax
Castle Dantoon Earl Suzzy 50 % 6200 176 gold |rename|
North Shores Mannor Sir Jimmy 25 % 4650 88 gold |rename|
Sea Cliff Keep (vacant) 25 % 4650 88 gold |rename|
What will happen is that Lords will no longer be able to collect 50% or more of a regions gold all on their own. If there was only a Lord of Giask (as listed in the original post) he would only collect 239g in taxes. This would be far less than what a solo lord of Giask could collect now (likely more that 900g per week). The only way for a region to reach it's full potential would be to fill it with knights.