Over his time in Phoenix, in games I have seen Ayton play, I was never overly impressed by him. About the only time I liked what he brought to the game was in the Finals. But the NBA is riddled with guys throughout their history that were good, not great, who had a great playoffs or playoff series only to go back to being good not great.
So, for that reason, I can understand the Suns reluctance to give Ayton that max extension. No need to rush. Let him start the year thinking he needs to prove something and if his game takes a leap forward, extend him for the max. If not, a less than max offer with incentives isn't such a bad thing for Ayton or the Suns.