If you had another dollar, then the value of the next dollar in utilons would decrease. Unless you're both an egoist and terrible with money, it will only be a slight decrease. After all, a dollar isn't much compared to all of the money you will make over your life.
I do not think that the fact that utilons do not add up linearly means that the conversion is not useful. For one thing, it allows you to express the law of diminishing marginal utility.
As per a recent comment this thread is meant to voice contrarian opinions, that is anything this community tends not to agree with. Thus I ask you to post your contrarian views and upvote anything you do not agree with based on personal beliefs. Spam and trolling still needs to be downvoted.