I haven't watched Icardi play enough to have much of an opinion of him and his playstyle. But looking through some statistics this morning I think there is some substantial reason for optimism about him.
1) He is super young, not much older than Batshuayi and younger than Morata while having accomplished much more than either. In 14-15, he had 22 goals and 8 assists playing most of that year as a 21-year-old and averaged more than a goal or assist per 90 minutes. Those kind of numbers at that age are ridiculously rare and he did it for a team was pretty mediocre offensively in general. His goal tally fell off this year but a lot of that seems to be due to team dynamics - his conversion rate went up but his opportunities went way down as Inter just struggled massively to produce chances.
2) His lack of involvement in the offense more generally might be exaggerated. In 14-15, when Inter was a bit more functional but still not anything approaching a dominant offensive team, he averaged about 19 passes per game. That is low for a striker but its not that far off some of the numbers that a player like Aguero has put up over the years (he has averaged about 23-24 passes per game at City) while playing for a team that regularly has 65% possession. Icardi has also averaged .9 and 1 key passes per game the last two years while collecting 12 assists in domestic league play and creating 66 chances (total over the last two years in Serie A). All of those numbers are equal to or better than Giroud's. Overall, I wouldn't argue with the idea that link up play isn't his strongest suit, but I'm not sure its a fatal flaw (Aguero's passing numbers at Atletico were similar for example) and his track record for playing the key ball in the final third is actually surprisingly good, particularly when you consider how shit the offensive talent has been around him.
3) His conversion rate is just really, really good. It could be just a run of luck but it could also indicate a pretty rare talent for finding the net, which is what this team needs more than anything.