Juventus wants to win the UCL, but they don't have the money to buy a top class striker who can guarantee goals no matter what. Look at who they had to go through UCL over the past five years: Matri, Quagliarella, Vucinic, Llorente, Tevez, Morata, Dybala, Mandzukic (I'm not even mentioning some of the subs because Jesus). Either people who aren't even Europa League material or has-beens or young lads, all cheap acquisitions except Dybala which was a lucky purchase because EPL doesn't follow Serie A all that much.
You haven't been following but Juve lost Aguero because of dosh, they lost Van Persie, even Dzeko (...), the only reason they got Morata was because of a glorified loan deal (they couldn't afford a few millions more for a regular contract like Schalke) and Tevez because they thought he was finished. Last year they couldn't afford Draxler so they had to give the #10 to Pogba to calm Adidas' rage and buy Hernanes as a filler.
The overall group is good but the strikers just are not: Mandzukic is utterly old school unremarkable mediocrity, Zaza is only good as a sub, Morata doesn't score as much as he should, Dybala is green yet he's alone in the desert. He got injured right in between EF legs against Munich because he had to take care of most of the attacking from midfield on so he got tired and eventually his legs gave up.
In two years Juve is going to lose Buffon, Barzagli, Chiellini and Marchisio are going to be 33 and all busted up. What do you expect Juve to do, to waste money on overrated names like Milik or Batshuayi and hope they deliver before the foundations of the team are gone and they're fucked?
So in my estimation, Juve made this assumption: we had Pogba for four years and we didn't do shit in Europe, the one time we got close to doing it there were not one but two hungry strikers ready for european competition. On top of that, Pogba wasn't even around until the second leg of the semifinals. Now, we can put pretty much anyone in the midfield, we can't do the same in the striking zone, not gonna work. There's no good deals like Tevez and Morata around so...yeah.
People underestimate just how much Juve wanted to sell him.