The thing is, the club has to protect itself here and 1 of the ways it does that is make sure theres no break clauses.
The club had to make the deal and plan for Koeman being a success, in order to add a break clause it would have left itself open for him leaving after a successful season. In the clubs ideal world Koeman would have got us 4th in his 2nd season then we would have had Barca and Arsenal coming in and getting him away from us, with the way they contract was they would have had to pay us 6m compo.
As it was, he fell so fast and so quickly that we were forced to sack him before he had even completed 18months of his very hefty contract.
Its unlikely Koeman would have signed a 1 sided contract which allowed us to sack him when we wanted without any cost, so as I mention above, that leaves a break clause which wasnt in our best interests.