Diesel engines why not more available in smaller vehicles ?

Everyone begged for years for a 1/2 ton diesel pickup. However, thanks to federal regulations, maintenance requirements for the emission systems and extra cost of heavily taxed diesel fuel has killed the market. In the past a lot of people wanted diesel pickups because they had more towing capability and a macho image. Today, no one buys a diesel pickup unless they have to ave one for towing purposes.