The thing about a series of National Opens within Europe is, that it would be a good 'break-in' for the Worlds. Countries that may be up for hosting the Worlds could get a taste of a big comp with foreign attendance under their own terms, as it were.
Greater links between National governing bodies will. I'm sure, minimise the little differences in the rules that require sorting before holding a big international event. Countries looking at a long wait before their chance to host the Worlds would benefit from hosting one of these in the meantime as well.
The only thing against it really is when would it be scheduled, it's bound to impact on someones domestic itinery?
"The Past is a Foreign Country, they do things differently there".