Because they need flashbacks for Hook. Now we know that WHook somehow met Lady Tremaine before and also had a daughter. They couldn't do this with the real Hook because at that time he was on Storybrooke.
Of course the whole thing is just an excuse to keep Colin in the show. But the question is does the show need Colin so bad that they had to write this contrived storyline only to keep him on the show? I know Colin is on contract, but couldn't they just use him as a guest character, appering here and there in flashbacks or such.
They could have used another character for that. Like Zelena, as others pointed out. Or heck, even August
But they've jumped forward so many years. What kind of flashbacks can they insert in for Regina and Rumple that they can't for Hook? It looks like they're only doing flashbacks so far that include the adult Henry anyway, so everyone's on a fair playing field for the New EF stuff. They're already getting a new missing time period to explore.
I agree, I guess they really did want to keep Colin on the show, but I think the character he portrays does matter somewhat if they intend to keep using him as a draw. I mean, I'd feel bad if the only reason he was let go was because Jennifer didn't want to continue, but they could've just made him continue portraying the real Hook and that wouldn't have made it weird at all.
I wouldn't. If the character doesn't serve the story anymore, they should be written off. I mean why Colin is different than Emilie or Rebecca? Or should we feel bad for every actor on every show that their character had to die? This is the business, jobs comes, jobs end, new jobs come. No TV show lasts forever so eventually Colin would have to find something new, probably next year...