Think about it. Nothing can work the magic that a properly specced WAN will.
Hmmm....not quite sure about that. I don't see why you should pass static data repeatedly over the WAN to take up bandwidth, which is where WAN accelerators score.
Trouble is, and this is where I suspect your comment is coming from, that these days we have 2/10ths of b****r all in terms of static data being passed around commercial networks - most of the traffic is either IP voice, or dynamically generated even if it is portal based content, or browser based applications. In this case, as you say, the WAN has to be correctly specced, monitored & managed