There aren't two clearcut sides to this issue, and I don't want anyone lining up into camps. In general, though, we see a pattern: campaigns that build up exclusive assets fail. Modeldumps enable brilliant new campaigns that succeed.
I think exclusive assets have their place, especially when they're key story elements, but when they're not, they should be made available for the public good as rapidly as possible. We're all in this together as a community, and with the exception of TBP and Wings of Dawn, no 'large exclusives pool' campaign has ever made it to release in the HTL era (and neither of those use HTL models, for the most part). When some of them finally do, we can judge the impact, but I doubt the benefits will be worth the opportunity cost.
Modelers should strive to get their work released, polished, and open to the community as rapidly as possible unless it is an absolutely indispensable storytelling element. Good use of a ship is far more important than first use, and public releases allow every single campaign project everywhere, including those by newcomers, to succeed.
This is why we have banks IRL instead of stuffing our money under mattresses. Money in a bank gets passed around and helps everybody out. It's capitalism at work!
EDIT: If model exclusivity was important for storytelling, there would be a correlation between model exclusivity and the perceived quality of a campaign. Yet of the community classics - Derelict, Transcend, BP, The Procyon Insurgency, Derelict, Wings of Dawn, Silent Threat Reborn, Vassago's Dirge - only one of them uses exclusive models in any meaningful sense. They don't seem to be necessary.
