You might be drawing the wrong conclusion, based on the French case at least.

I don't think the sub-group that enjoys "the bigger the better" is an anglo-saxon phenomenon at all, whether in Fantasy or not. There's the same group of readers who salivate over door-stoppers, in Fantasy, or in thrillers, or mainstream novels and on and on, and there are those who like it short and sweet and who prefer stand-alones over series. It's not like Americans invented "pop lit" door-stoppers.. just think of Tolstoy, Dumas, Marcel Proust, Victor Hugo, Balzac, Yoshikawa, Luigi Natoli, Sue etc. Most of those fall in the "popular literarure" and "best selling" category (esp. Dumas, Yoshikaw, Natoli, Hugo, Sue), and all of them wrote HUGE books, often multi-volume stories. You'll find the same group of "big books" and never-ending sagas in Russian literature, and Scandinavian literature and I suspect in most others. Japanese love serialesque stuff a lot too, and apparently WOT sells very well there.

In Québec, one of the biggest bestsellers in recent years is a 10-volume (all door-stoppers) series written over nearly 20 years. The final two volumes have outsold The Lost Symbol locally.

I think "big" has pretty much the same attraction here it has in the US/UK, as far as Fantasy goes. The reasons American Fantasy (and most of SF) door-stoppers sell poorly in the French market are more:

- It is very poorly marketed and basically not publicized. Fantasy has nowhere near the exposure of other genres, and it doesn't come even close to the exposure it gets in America (which is small, compared to mainstream and other genres). American Fantasy writers are pampered cry-babies in comparison to how the genre is regarded in French culture.

- It's fairly recent that the genre enjoys *any* popularity (again, I would say.. we have classics of related "supernatural" lit. - even Dumas wrote in that genre a bit), and it's due in part to the LOTR revival with the movies, and to Harry Potter. Classics like Narnia didn't even interested any publisher in France before Harry Potter... It's only then it got its first translation (that didn't sell very well). The genre is a good 2-3 decades behind its state in the Anglo-saxon market, the post-Tolkien phenomenon is largely unknown in France and French-speaking countries, aside from a "fringe" phenomenons in the teenager audience. There is presently a "wave" of Fantasy written in French, some properly post-Tolkien and more post-Potter but so far it's by and large a children literature phenomenon. For adults, you pretty much need to be Susannah Clarke to break the genre barrier and get to the top of the BS list, and quality aside, that has something to do with the fact she was backed by a major publisher in translation too. Writers like Anne Robillard outsells Jordan or Martin many times in the French market and pretty much matches stuff like Twilight, and quite a few others do as well. Fantasy for adults is still very rare and the less popular "elitist" Fantasy like Gene Wolfe's doesn't even get translated (it wouldn't sell). There's Elizabeth Vonarburg, heavily influenced by the golden age American SF and Guy Gavriel Kay (whom she also translates, and very well too). She's pretty much the French-Canadian GG Kay, writes really well and unlike most American writers in their market she's pretty much considered on the same footing as the mainstream novelists by the critics and milieu, but her sales are modest (she makes the best selling list here, the mainstream ones, but not for long and nowhere near the top). And oh... she writes 500-600- pages books, most of them 5-6 volumes series.

- Most of Fantasy isn't released by major publishers (who consider it trash, to say things plainly), and most of those books can't be found reliably. Very frequently they're back ordered and you have to wait months and more for them to get reprinted. Waiting months to get to read the middle of A Game of Throne or a WOT book, that's very discouraging, especially when you can't be sure it won't happen again further down the line. Many friends who unlike me read translations have given up on several series for that reason. There are a few exceptions to the rule, for instance a few anglo-Canadian writers like GG Kay have been picked up and translated by a high quality small local publisher (also Vonarburg's, and our one and only genre lit. publisher). Kay most likely outsells Jordan, Brooks, Goodkind and Martin combined (in translation only, they sell loads in English though).

- The cultural strength of English means most of us read a very great deal more of foreign works in translation than the average anglo-saxon has to. Our standards got higher for their quality, and most Fantasy literature, even the best-selling writers, gets extremely poor and cheap translation (the sort Harlequin books get), beside the precious few that become a phenomenon and gets picked by the major publishers (like Harry Potter and Lord of the Rings, Clarke and the likes). If you think Robert Jordan writes poorly, try him in French. It's atrocious.

- Finally, there's the financial issue. Most American Fantasy in translation is read by teenagers. A third of a Jordan, Martin, Brooks and co. book sells for a higher price than an hardcover in English does. A shabby paperback of a Jordan book (a third of an original WOT book) that makes Tor's PB look haut de gamme sells for over 15 dollars. Do you think Martin, Jordan and co. would enjoy nearly their popularity if people had to pay over three times the price they pay now to read them? How many would buy a 100$ HC of WOT? A 50$ PB?

And you know Larry... reading in at least two languages is sort of exceptional for Americans. That's not really true here, and even less so in Europe. Just judging from my extended personal circle, I more than a little suspect in a lot of markets, especially in Europe and Québec, a very great deal of American Fantasy lovers just don't bother with translations and read those books in English, and more so now than years ago. You'd have to look at the foreign sales of Orbit (and some of Tor) to get the real picture of sales for Jordan, Goodkind, Brooks and most of the "big names" in those countries. They sell more than in looks, only not in the local language.