The top 4 thing shouldn't be underestimated IMO, as you say some clubs have thrown serious money at it and not consistently managed it. And there's no question that at times during the stadium move our finances were somewhat restricted, certainly compared to the clubs with sugar-daddies, and I think Wenger did overall a pretty good job keeping us in the top 4 in that era. Where he's failed though, and this is why he needs to go, is to push us on now the money is there and we've started signing players that should have pushed us on.
A load of nonsense has grown up around all this - I guess because of people's frustrations: "Wenger doesn't care about winning", "Wenger's under no pressure and would keep his job no matter how we do", etc. All rubbish. And the last 3 seasons haven't been the complete abject failure some make out. 4th and the FA Cup, 3rd and the FA Cup, 2nd. But we should have won the league last season, it was our best chance to for years, and if Wenger couldn't win it last year then I don't think he ever will again.