It really annoys me here in Australia how the Rugby World Cup is often referred to as the "Real" World Cup (hence implying that the Rugby League World Cup is useless). This term is even used amongst some league fans - those who despise International RL. When I was at my parents' house in the Hunter, I was listening to the radio and how some sports reporter (who's a mad Knights fan) - during the news break - said "There's going to be a Rugby League World Cup soon. However, I look forward to the "Real" World Cup in 2015.
As you said, the League WC started in 1954 (2nd oldest World Cup of any football code behind soccer, which started theirs in 1930) and Union didn't have a World Cup until 1987.
And regarding respectibility, I acknowledge at the moment that only 3 countries - Australia, New Zealand and England - have a realistic chance of winning the RLWC and unless one of the 2nd-tier nations below the Big 3 pull off a Houdini string together a combination of a lot of luck and solid performances, it will still be at least another decade before a team outside the Big 3 at least makes the final. Until then, there's a 99% probability the final will either be Australia/NZ, NZ/England or Australia/England.
In Union, only 5 countries - Australia, New Zealand, England, South Africa and France - have a realistic chance of winning their WC (that's right, two countries more than the RLWC). Don't let the Unionites lie to you. Yeah, ok, the 2nd-tier nations - Ireland/Wales/Argentina/Scotland - are competitive and will pull off the occasional upset against the "Big 5" mentioned, but they don't have the resources and talent pool in the long-term to win a world cup, as soccer stand head and shoulders above every other sport in those countries. Surprisingly, the Big 5 are the only 5 teams that have made the final of the Rugby World Cup since its inception in 1987. Where the big difference lies is that the 2nd tier nations in Union are much better than the 2nd tier nations in League, and THAT is what perpetuates the illusion that Union WC is more 'competitive' than League, when in reality, despite having a 20 team tournament, the WC really is battled out between only 5 nations.
RFL's challenge is to try and bridge the gap between those 2nd-tier nations in league and the Big 3 over the next decade. A good starting point is scheduling more test matches for them, hence acquiring the experience. However, IRL will always be perceived by the neutrals as a joke until the eligibility laws are tightened (not just being eligible to play for a nation, but also stopping players from jumping back and forth between nations). I know they pulled off an upset in a warm-up match against England last week, but the Italian team is an absolute joke, comprising mainly of NRL players who are claiming allegiance on heritage. Watching them during the national anthem last night was embarrasing. The U.S.A Tomahawks team is even more of a joke, and no wonder the majority of Americans simply couldn't give a stuff as they can't identify with their team where local "American" players have been shafted in favour of nuffies like Clint Newton