I think the reason most doubt him is precisely because they acknowledge our midfield is garbage and are skeptical of any incoming midfield transfers. It really isn't hard to be better and more consistent than our mids, whether individually or as a unit - they are nothing special!
People are skeptical because of how our recent midfield purchases, McNuggets aside (still too early as well), have panned out. Additionally, some of us are concerned that he'd be the marquee or key signing in midfield, which would be slightly underwhelming and nowhere near sufficient to take the midfield to the next level (where it should and needs to be). Having said that, I'd gladly sacrifice all our mids if we can bring in Locatelli and someone else of quality.