Worlds invitations are not based on skill. They're based on earning points. You don't have to win or even place well to earn enough points to qualify, you just have to attend enough events to accumulate them (though obviously the better you are, the fewer events you need to get the minimum).
They've given EVERYONE several months notice as far as the timetable for registration goes. The registration schedule was announced at the end of last year, not four days ago. If the players that "deserve" to go to Worlds the most can't plan 4-5 months ahead to be in a position to sign up the instant registration is open to them, I don't know what to tell you.
If the PDGA is going to change registration criteria to be ratings-based, then they need to announce their intentions of doing so before qualifying even begins. In other words, it's about 15 months too late to be changing anything now, which is why they haven't added a ratings criteria.
If you want ratings criteria for Worlds, it has to start no sooner than 2016 Worlds and even at that, it has to be decided NOW.
I agree with this IF it doesn't fill nearly instantly - and time will tell on that one. But if it fills within minutes and he with the fastest connection ends up winning than this could get ugly.
I actually do like the points system and wouldn't mind a tiered registration based on points for worlds. That way the big time touring pros would still be given a reasonable time to sign up based on the points they have earned since they earn them at a higher rate. For your "average" pro - get to a lot of tournies the prior year and earn it.