Although Paris is the most visited city in the world. It also has a reputation amongst the global cities as being unfriendly. Enough that the Paris Tourist Board and Chamber of Commerce have launched a campaign to educate service workers on treating tourists better. Tourists also do not spend as much money in Paris. It is number 3 in that regard. This is likely due to Paris' centralized position. It may more likely be a stop-through on the way to a visitors' final destination.
You can be perfectly fine on English in almost any large city in the world, but there is more of a friction in Paris when interacting in English than in many other European capitals.