OK, I see the point of these. Have extra manufacturing, pump it into something else. Birthing Subsidies is a godsend, and Cultural Festival, well, I'm using that to fook over the #1 power player right now, who happens to not be a warmonger (Iconian).
But Research Project and Economic Stimulus are BORKED. I tried it on a planet where I had ALL Manufacturing (and yes Marigold, an approval building, as well as some farms), and I tried to see which was better, to put population points into Research or Economy, or use my awesome manufacturing capability with the Research Project or Economic Stimulus. In all attempts, using population points won! In every possible way.
The bonuses from Research Project and Economic Stimulus are therefore too weak to even matter at the moment. I'm not asking for huge buff, but it needs to be increased to be worthwhile in those situations where you need all the research or money you can get in a short run, at the sacrifice of A LOT of manufacturing.
I wonder if the AI is using this, at times, to compensate for empire wide shortages? If so, its shooting itself in the foot.