Most because it was overkilled.
I'd have a regional 7's tournament in say early 2015 with International teams only but only from the local region - so UK would be Atlantic, UK & Europe - Australia would be Pacific Region. The top teams qualifier for the World 7's.
Then every four year, starting in early 2016 have the proper World 7's. I'm not talking about match ups like Souths vs USA. I mean you'd break it up and structure it into pools hosted in 3 or 4 cities catering to local interest. For example, if Brisbane were to host you might see something like:
Broncos vs Titans
Queensland Country vs Queensland Metro
PNG vs Fiji
Cowboys vs Brisbane#2
Indigineous vs somebody else
etc so the different matches from the seperate pools are buffered out amongst each other. More fans go because their NRL or SL team is involved but they also get to see special local rep teams and the internationals are the icing on the cake.
Say for instance in Melbourne, you'd have Storm in the NRL pool, a VRL team in the Rep pool, then International teams that appeal to locals, maybe Greece & Italy etc
Auckland you'd have the Warriors, Maori side, some Polynesian national teams etc
Sydney you'd have the Sydney NRL club sides, maybe a Country NSW team, Lebanese in the International etc
It would be in essence more like a 7's World Cup in a miniaturised format played over 3 days with the finals on the Sunday. It would only be hosted in Australia every 8 years so NRL teams would only be involved every 8 years.
That said because there's prizemoney on offer, NRL teams might be inclined to send squads overseas and Super League might send them here. People are always talking about great inter league competition - well here's the opportunity.