Yeah, I think the financial incentives lie at the heart of it. While there are people who are just jerks, a lot of the jerkish behavior is because it's incentivized: if you're thrown into a hyper-competitive environment where you're pitted against other researchers for a limited number of tenure slots and grant funding, it doesn't encourage sharing. You could share that great data set you collected, but all you'll get in return is some fuzzy thanks, while if you keep it proprietary you might get another 2-3 journal papers out of it, which'll get you tenure+grants.

I think fixing those incentives is the key to fixing that. Alas, I see it mostly going in the other direction: universities are moving more and more towards a quantified business-type model, where professors are judged wholly on money brought in and publication metrics, and the competition is only getting fiercer. If someone wants to be open/sharing/generous with research and have a job, it's not impossible, but it's fighting against the system more than with it.