It's funny. I justified keeping Stastny during 2013-2014 for the exact same reason. It was about proving to the team that we wanted to win, it was about getting our young players valuable playoff experience, and it was about proving to a disillusioned fanbase that times were going to change and we were going to be serious about the playoffs. I justified losing Stastny by saying the 2nd round pick+prospect we could have gotten for him did not outweigh the benefits of keeping Stastny and the psychological message / impact that would have on players and fans.
How did that one work out? As a fan, do I feel...happier, right now? No. Did the players really benefit from that run? No, they've completely stagnated. Did the players get a psychological boost from seeing this team was serious about winning? No, they've completely stagnated.
I'm afraid I've already gone through what several of you guys are doing right now to justify the deals they've made, and I've already seen how it turns out.