How anyone can say it's lost a step, or it's losing credibility isn't working with a full-deck. Why would anyone assume it's lost a step? Because they Super-sized the pleasure of the entire event by adding 2 of them? NO.
It's not like it's the same exact thing. Because it's all about who's involved, and you have a total of 12 different names, styles, and overall individuals making sure that neither Chamber match is the same.
No Way Out used to be a complete skip Pay per view, and suddenly now it's a top spot before WrestleMania. The concept of having 2 Chamber matches before Mania is adding an element of the unknown on what could happen to set up Mania matches, and the prime example of that, would be this year's No Way Out. I'm almost sure NOONE could've called what happened to happen.
People can argue "Well, they aren't hosting two Royal Rumble's in one night" Well, no shit. Because the Royal Rumble is only designed for ONE purpose. Whereas the Elimination Chamber can host not one, not two, but three possible purposes. Championship matches, Contender matches, and overall Grudge matches. It's definately worth having 2 per show.
And finally, unlike Hell in a Cell, unlike Ladder matches. The Chamber match isn't getting sold-out on just any Pay per view, or more than once a year.. it's become solid for now being at No Way Out, and it's only ONCE a year.
So in the end, the Elimination Chamber hasn't lost any credibility.. if anything, it's GAINED more by becoming an even more impressive and dangerous match concept, to host and sell so close to the biggest show of all time, WrestleMania.