In the end, who are the Politicians representing? When the interests of the multinational corporation come in conflict with the interests of the general public, who wins? In a market economy the one with the money wins, should the same be true of the government representation too?
Ultimately, markets have a built in bias towards the top. In a theoretical perfectly functioning market the money will accumulate at the top until one person controls all of the money, at which point the economy completely collapses. Despite this flaw, markets are still the most efficient way to allocate resources and grow the economy. So the best solution we've found so far is to have the Government act as a backstop, draining money from the top and feeding it back into the bottom so the market doesn't collapse itself. Unfortunately, governments sometimes forget that and their economies suffer.
Plus, despite what many economists may think, money isn't everything. Money is only a means to and end, where efficient distribution of resources provides the greatest overall happiness in the population. A system where half of the population is abjectly poor and 0.01% are so rich they have no idea what to do with their money except to use it to make more money has failed.