...it wasn't like NASA was about to do something huge and cooperation with India puts that goal at risk...
Your nested counterfactuals are a little hard to unpack, but if I understand you correctly, it is somewhat the contrary, at least with NISAR. (Oops, I added another counterfactual.) NASA was about to NOT do something huge and the collaboration enabled it happen.
That is, before it became NISAR, the Earth-observing biomass/seismicity SAR mission was called Desdyni (http://decadal.gsfc.nasa.gov/desdyni.html). This mission was referred to as desirable in a 2007 National Academies decadal roadmap (covering the next 10 years), but there were too many other even higher-ranked missions in the pipeline. So it seemed like Desdyni was not going to get on the NASA roadmap any time soon.
The Indian contribution seems to have (for the moment) been enough to get it going, because in February NISAR entered "Phase A" which is NASA-speak for "we are starting the mission". There are later decision points depending on how ready the overall concept proves to be.
"The ISS is incredibly more expensive, complicated, and accomplishes less science because it's "international.""
Accomplishes less compared to what? Skylab? Mir?
The ISS is designed to host up to 7 crew members. For purposes of comparison, Mir could host 3. What makes you suspect 7 astronauts can do less scientific work than 3?
Skylab was cheap(er) because it was launched in one single stage (IIRC it literally was a Saturn V cargo bay).
The ISS was designed to be built up over several years, over several launches, with each launch costing much less than Skylab but obviously more overall. It was a design decision that favoured amortizing costs for an age that couldn't afford another Skylab.
On the other hand, "international cooperation" is often the death of many projects, particularly space projects.
On the other other hand, it wasn't like NASA was about to do something huge and cooperation with India puts that goal at risk.