I think the plan was originally to use Galchenyuk as a center but a number of circumstances changed that for the worse.
1) - The lockout: If half the NHL season doesn't get locked out than I have my doubts that Galchenyuk would have made the team. He'd have another full season developing at center with Sarnia. Hindsight probably tells us that would have been a better path to a full time center position.
2) - Winning the division in 2012-13: It created expectations. We all of a sudden went from a team that was rebuilding to a team that was on the brink of success. We were Canada's next cup. We have a Norris winner in Subban. We had an elite scorer in Pacioretty. We had top 6 centers in Plekanec and Desharnais.
3) - Conferance Finals in 2013-14: Coming into the season we were favorites. But we had holes on the wing. Desharnais wasn't suited for the wing and we weren't moving Pleks. In Desharnais' defence, he had a good year. So we kept Galchenyuk on the wing for another year. Short term we were probably best suited for him to be on the wing. Our success' and the expectations that they created became our worst enemy. We have a bad regular season, hope that maybe there will be some change... and Boom, we get hot in the playoffs. Conferance Final run. And the vicious cycle continues.
4) - Another Division Title 2014-15 (le sigh) : Again we are Canada's hope. Experts are predicting we are going to have a legit shot. And we actually look like it. Pretty convincing season. We need Galchenyuk's offence, but our best top 6 has him on the wing still. Desharnais is productive. Plekanec is productive. Again, his conversion to center gets delayed. Again in the short term it probably is for the best. Again it doesn't get us anywhere.
So here we are today. Hindsight wishes we just put Galchenyuk to center. Circumstances kept him on the wing. I 100% believe that had we missed the playoffs again post lockout, had Galchenyuk played a full season in Sarnia, had we gone into that 2013-14 season still "rebuilding" that Galchenyuk would have come into the league and played center right away. Unfortunately the pressure of the teams success and expectations got the better of the team. We entered a win now mode and we are feeling it now.
So do I think that the team drafted him to be a Center? Absolutely. But I think with all the successes the team was having, they just got too comfortable with him on the wing. Took their minds off the long term for a minute and now we are feeling it.
What you call circumstances were simply bad decisions which we didn't even need hindsight to know they were bad.
In 2012-2013 Galchenyuk played 14 out of the first 15 games as center. This was the moment Therrien decided Galchenyuk wasn't ready to be center and almost permanently moved him to wing.
The production of our centers at that time was
Plekanec: 13 points playing mostly with Gionta & Bourque
Galchenyuk: 9 points playing mostly with Gallagher & Prust
Desharnais: 7 points playing mostly with Pacioretty & Cole
Eller: 6 points playing mostly with Moen and Armstrong
So claiming that we used Galchenyuk at wing because of expectations, or being focused on the short term is complete BS. Galchenyuk was the better player even as a rookie. But Therrien either didn't like Galchenyuk or loved Desharnais so much that nothing would change his mind.
Despite playing on the 1st line Desharnais was outproduced by both our 2nd and 3rd line centers that year. It was clear as day that he wasn't capable of being a regular top-6 player and that Galchenyuk was the better player. And if that season wasn't enough, Desharnais proceeded to put up 1 point in 19 games yet we refused to give Galchenyuk a chance at center during that horrible slump. How can you claim short term we couldn't play Galchenyuk at wing when our #1 center produces 1 point in 19 games?
If we were actually only concerned about short term success like you are claiming then we would have played Galchenyuk at center because he was our 2nd best center behind only Plekanec, and had the potential to be way better. But we didn't actually focus on short term success we focused on trying to get the most out of Desharnais so no matter how bad Desharnais was he was locked into that #1 spot, and because we used him as our #1 guy we needed both Plekanec and Eller to cover the defensive side of things because of how bad Desharnais was.