Capitalism is fundamentally flawed as it exist's on the basis of a profit motive which by its nature requires workers (the majority) to be constantly exploited, ie not be paid what their labour is worth. This creates a division where by all profit is skimmed to the core from the periphery.
Trickle down policy has been proven time and time again to be a fallacy, in actuality money is continuely sucked out away from the periphery to the core (elite).
It may appear that inequality has lessened due to the progression afforded to the masses of western countries in terms of technological and material advancements (under a capitalism system), however not only is this not the case in terms of capital, there is a huge amount of exploited (mainly in developing countries but also here) paying the price for these luxuries.
You may ask why inequality is an issue if you are of the neo-liberal persuasion, it is an issue because countries with high levels of inequality have proved time and time again to have the biggest social problems, this includes high crime rates, high mortality and morbidity rates, high suicide rates, low employment rates etc. Problems which affect both rich and poor.
On the other hand socio-democratic countries such as Sweden & Scandinavia have proved the benefits of state ownership and a peaceful and democratic move away from the constraints and fundamental flaws of capitalism. They consistently do well both economically and socially in terms of gdp's and things like employment and education.
I believe Marx was right when he said capitalism would lurch from crisis to crisis, papering over the cracks, before eventually destroying itself. This is evident by the unstable nature of the economy and the predominance of recessions. Really how stable can an economy which relies on solely both on people spending ubove their needs and earning less than their worth really be? Not very! The only people benefiting in the long run are the bourgeois (and for a limited time only the petty-bourgeois). You say that socialism is evil because of the stark visibility of those who have done evil things whilst also in some way attempting to follow some variation of socialist principals, but what about the core root of capitalism which exists on, and only because, of constant exploitation and greed?!