A monopoly is a direct attack on the free market and therefore upsets true free market believers.
There is nothing inherently wrong with a monopoly. If I build a widget that no other company cares to build - I have a monopoly and that is perfectly ok. The problem comes when I abuse my monopoly position in the widget market to either stifle competing widget manufacturers or unfairly benefit my sprocket offerings - which is essentially what the EU Commission is accusing Google of doing. Does Google do this? I don't know and honestly I don't care. But, then again, I don't spend a whole lot of time using Google products so I guess that somewhat speaks to their (lack of) ability to manipulate markets for their non-search related services.