Keep in mind that the OP's situation is likely very different from your own.
You value WDW and DL because you can have an affordable holiday abroad where people are friendlier and it may be more cost effective based on exchange rates, etc. Going to the continent for you is likely neither exciting or novel. That's valid. But it has almost nothing in common with Disney.Mike's situation other than it involves Disney in some way.
Disney.Mike's profile says he is from Louisiana. Going to WDW is the easiest and most accessible way for him to get his Disney fix, and if he's like many people on this board, WDW may be presently lacking either in novelty or affordability. Paris may not fix the affordability piece, but it's at least something different that will definitively offer something he can't experience in the states.
And when there are so many people on this board and others who simply have no interest in venturing to other Disney parks, and so many Americans who are so convinced that the rest of the world, even Europe, is a scary place, or that the US is the best place in the entire world, the last message that needs to be spread is "stay home and just go to WDW."
I advocate for everyone who can to try and visit all of the parks around the world-not only does it give you access to fantastic attractions and parks, it makes you a more informed fan. I believe that if more people were more informed, all of the parks would be better places, period. And, again, Paris! A city which will always have far more than Orlando will ever be able to offer, unless you really want nothing but theme parks for two weeks.
Ultimately, even if he goes to Paris and hates it, or finds that you were correct, he will be richer for having made the journey. I can't say the same about a repeat visit to WDW.