For us a chance of manager has seemed inevitable for a while now the situation had gone beyond any alternative.
Generally all clubs fans inevitably always have aspirations of achieving far better, even if in some cases that's realistically unlikely or even highly unlikely, and being better entertained. The second of those is a very valid reason as it's an entertainment business and they pay good money, it has to be reasonable to expect something better for it. Change though can be extremely risky where there's a minimal realistic short-term upside in league position and a far greater potential downside and can exact a serious price in loss of status and revenue if things go wrong.
The financial implications of a real downturn and possibly relegation can be catastrophic unless the club has had a low spending model to cope as Burnley did.
Sometimes, and especially far more so now with social media, there can be such a chasm and split between the fans and current manager that it becomes irreconcilable, and it's almost inevitable that the board or owners take the populist route of changing, whether or not that's even sensible or better.
Owners and the board always want themselves to be seen in a more favourable light too and that can be a major driving force behind decisions.
West Ham's board look set to make a managerial change too, in their case entirely for political purposes as they strive to make some ground with their disenchanted fans having already alienated so many with their move away from Upton Park to an athletics stadium.
...free season tickets..special treatment ..etc...etc...
