He is a great player, I don't dispute that at all, or that we would be great for us for a few years.
It's the fact that we have a big age gap in our squad. Taking aside Gundogan (34) and KDB (33), most of our players who have been playing or could play in central midfield are a similar age: Kovacic 30, Bernardo 30, Grealish 29,
Add in those covering: Stones 30, Akanji 29.
And Rodri is 28.
Then we have a gap, and taking aside Nunes everyone else is 24 or under.
So in my view if this squad refresh is supposed to be a proper rebuild, with some thought to succession planning, you don't want to store up more problems in 2-4 years' time by buying another 29 year old.
But assessed purely as a player in his own right, Kimmich is class, obviously.