Why investors shouldn't dismiss whole asset classes

You are either positive on an asset, or you are not. You either think GEM is a value opportunity, or a massive risk to avoid. Of course, there is always some consensus. European equities look good, the UK and US represent reasonable value and, of course, Japan is now worth an allocation. But, by and large, there are very few 'shades of grey' in the world of investment at present, which slightly confuses me. What is driving this trend? Is it the multi-asset, multi-manager funds which are positioning themselves on asset allocation calls? Is it because we all love reading stories abou...