I didn't see many engineers the last two years demanding pay decreases because of the money they save by not having to commute to work...
* higher utility and Internet bills
* increased wear-and-tear on the house
* purchasing equipment and home office furniture out of pocket or using your existing tech equipment
* increased vehicle maintenance cost (decreased usage lead to more rust, damaged batteries in the cold weather and selling is ultimately not worth it, at least in my case)
Engineers saved time, yes, but not as much money as you might think.