Half witted, biased article.
1. Roof: RG is played inside the city limits of central Paris. It took them for ages to get all of the agreements, and fight all of the neighbour's appeals, to revamp the stadium. All of the other slams are played in distant suburbs. And there will be a roof next year.
Hawkeye: is more debatable, but apparently not 100% reliable on clay because of the dust (i.e. Hawkeye could give a ball just out, when the dust moved by the impact could show it just clipping the line). There, though, I agree that if a technology was found to be reliable, it should be used.
2. Crowd: empty corporate boxes are an issue everywhere. To give the example of the semis this year, on a day where a terrible storm was battering France (and killing 3 people of the Atlantic coast), is biased at best, dishonest at worst
3. Predictability: it's only down to one factor - the monster that is Rafael Nadal. Being "the least competitive surface" is nothing short of a joke, when European players, who have dominated the game for years, mostly grew up on that surface
4. Boring: if one is just interested in people bashing into a ball and relying solely on power, maybe. But clay forces you to think a lot more, develop a strategy and add variety to one's game, like the ability to use drop shots and conclude at the net. Again, to say that "very few feel totally comfortable" on the surface is a joke when the vast majority of European and South Americans grew up on the surface.