It's because you need to send something that needs to work on very tight energy budgets, after 10 years of radiation exposure and extremely cold temperatures, a

It's because you need to send something that needs to work on very tight energy budgets, after 10 years of radiation exposure and extremely cold temperatures, and on tight bandwidth budgets. They're lifespans and conditions that are rarely considered when designing cutting edge tech. If you only get one shot at setting up for a mission that won't start gathering data until 10 years later, you probably don't want to take a state of the art camera up there, you want to take a decent camera that you're pretty sure will work well after 10 years.