I agree

"il n'en demandait pas tant" is a headline with insufficient meaning, but it's done on purpose : people will ask themselves" il n'en demandait pas tant, de quoi ?" so it acts as an incentive to make people read the article. Don't english newspapers have the same strategy of exciting curiosity ?

Yes, they have exactly the same strategy. Nevertheless, there are cases where something has a basic meaning in French but no meaning in English, because of differences between the two languages with respect to syntax and the way ideas are expressed. The problem here is that we are dealing with two issues:
1) What is the core meaning of "n'en demander pas tant"? I for one would still like to know what "en" refers to.
2) How would an English-language publication have worded the title of the article? If the idea is that it was an easy win for Tsonga, it would be possible to be quite specific in English, without using more space than that used by the French title: "Tsonga strolls to victory", or something like that.