That would really screw the taxpayer. The employer usually pays about 80% of the premiums. So for a single person, add about $5000-7000 to his income. Depending on the health plan, you can either have a fixed co-pay or a deductible or pay a percentage of the charge each time you have an expense. So if you have a $10-30 co-pay every time you visit the doctor or get an x-ray or a lab test, that is an out of pocket expense. Do you think most people are going to have out of pocket expenses equaling the $5000-7000? Not likely. Good for Obama's treasury, bad for the average citizen.
There are many other employee benefits other than health insurance that would fall under the proposal of adding them back to income. The standard at a company I am familiar with is 32% of payroll is the cost of benefits. Imagine if your reportable income went up 32%, but none of that went into your pocket because the company was spending it to give you benefits. That's scary.