Sophie, I see this as a political move. The Paris City Council is loathe to spend euros on RG for local political reasons that vary from one member to the next. The politics have caused such an absurdity as the fact that there are no lights.
Last night Ivan Ljubicic said, shortly before his match with Mardy Fish was continued till today, "This amounts to player abuse. Spend some euros and get some lights." At that point, I believe he started to swear and also lost his concentration. Ivan Ljubicic is not some young hothead. He is a recognized leader among the players, arguably the second most influential player in the top 20 after Federer. It was a message he very much intended to deliver.
Now they're threatening to move to another location, in effect thumbing their nose at Paris and most especially at the City Council. Good for them. Let's all hope the City Council are not so foolhardy as to call their bluff. They most likely will move -- and it will be to everyone's detriment.
So let's all join with Ivan Ljubicic and proclaim in a loud and unified voice: "This amounts to player abuse. Spend some euros and get some lights." Spend some Euros -- or risk losing Europe's premier tennis tournament. It is, after all, along with Wimbledon, one of the two greatest tennis tournaments on earth. There's a split of opinion about which of the two is the greater. It's worth the investment. Paris should not be without it, and the players and fans should not be deprived of Paris.