Many (even most?) people do have freedom as part of their utility function, but at different weights, so redefinition is unnecessary if you grant a moral imperative to increase the utility of others.
The problem is that most people interpret such an imperative as “increase the utility others would have if they shared my own utility function”, which is not at all correct. Simply redefining utility in the general case to include freedom is in this class of mistakes.
Many (even most?) people do have freedom as part of their utility function, but at different weights, so redefinition is unnecessary if you grant a moral imperative to increase the utility of others.
The problem is that most people interpret such an imperative as “increase the utility others would have if they shared my own utility function”, which is not at all correct. Simply redefining utility in the general case to include freedom is in this class of mistakes.