Congress doesn't need the expertise to write the regulations. The elected Congress could just vote to pass the regulations as laws. Congress just doesn't want to be on the hook for the regulations, which is part of the reason why they hand off law-making to the agencies in the first place.
Theoretically, this approach would give people a greater voice in the rules that govern them. Sadly, in practice, we can't seen to rollback the proliferation of criminal laws that embolden prosecutors and lead to an unfathomable number of people in jail that have not been convicted by juries.