The notion that if you have more than one race in a country, it takes away its "World" element is pig-ignorant. Simply put, race where people want you there...
(Take this with the good humour it is intended with, but just too good an opportunity to miss ..... )
So it'll end up like the baseball 'World Series' then? - haha. As an aside to that remark, one of the companies I work for (interestingly, it's European based) has two main branches, NA & WONA which stands for North America and World Outside of North America, it's purely revenue based and represents an almost 50/50 revenue split, but 7 years later it still makes me smile :-)
Back to the debate and specifically, the fans.
One of the reasons there are still droves of empty seats at WEC races is that tickets are still expensive. Events like LM, Sebring and Petit are always going to shift boatloads of entry tickets but IMO the other venues should be either giving them away (register online for free tickets etc.) to gain a huge marketing database or selling them at a huge subsidy, say 5€ or equivalent local currency. Everyone loves a freebie and people who would not usually go will, familys will turn up for a day out rather than just the die-hard dad and one kid (excuse the stereotype), and hopefully, enjoy the day. As GF rightly says, the revenue derived from the fans overall is negligible so such a concession would cost virtually now't in the grand scheme of things. Renault do this yearly in the UK at Donnington and lately Silverstone and the place is packed. While Renault initially subsidize it as a promo event, the tracks make back any initial loss (and possibly more) at the concessions stands - there has to be a way the WEC (or if doomed, it's successor) can pick up on something like this?
Don't crucify me for this next statement, but there is a reason drugs dealers give stuff away at first, once people are hooked they need to feed that addiction and lets be honest, racing is one of the biggest drugs out there !!