In the ideal world sure, but it's a lot simpler on paper than in practice. If you can raise the money to buy more Pepe's after signing a Partey, Ceballos and perhaps another centre back, super. But what if you don't have the money to do that? Arteta wants a quality winger, we can't afford a proper long term solution. Do you tell him to suck it up for a season and pray he gets us to the top four regardless, or do you give him what he needs to get top four which would then actually give you a much better platform to implement the strategy you speak of?
Everything is not black or white in our position, that's just the reality of our situation. There's going to be lots of grey needed to get where we need to and it's managements job to make sure it's not just a waste of resources. I don't know whether that's Willian or not, and fwiw I don't believe any of these rumours, but if it is, so be it.