Nothing lasts forever. A pad will eventually wear out. No guarantee that regulating voltage will make the pad last longer.
And many people in the industry would have a big problem paying $140 to regulate a $20-30 pad. Personally I like heat regulated rooms, decent sized cages and hot spots created from above whenever possible. I'm looking at a new heating system for my room that will heat or cool as necessary. I'm spending a mere $900 on the setup which will create my ambient cage temps. People need to invest or take risks as they deem fit.