Even these "cheap" missions are a half billion each, so it's a little more than nominal. Choices have to be made, even if NASA's budget was doubled.

TiME was always a longshot proprosal, but I'd personally rather see the lower budget Discovery Program missions doing riskier stuff. And while I love a good Mars mission, Mars gets all the marquee missions anyway. It's kind of a shame to see it eat the resources of the lesser missions too.