Good chance many of those items came FROM Goodwill, Salvation Army, etc. They'd be equally strapped for space, and less likely to know what do with the stuff. The co-ops / kitchens tend to be the "last stop" for bikes/parts that haven't found the right home. If it weren't for liability issues and concerns for people really trashing the place, they could consider an "interim" container that's easier to access than the dumpster. But they're probably also strapped for the human resources needed to keep something like that from becoming a complete disaster.

Overall, it is a shame what good, usable stuff goes to waste. Around here, the number of bikes abandoned (but left locked up) by students is breathtaking. Yeah, a lot of Wal-bikes, but a lot of desirable C&V gear as well. We just have to find/pick what we can, use the skyhook when it's called for, and hope that there are others out there digging up these old coins and keeping them in circulation.