Four years ago isn't classic. But to answer your question...the streak ending. Which I also feel was the start of the demise of WrestleMania. The Streak not only gave Undertaker a legendary mystique at WrestleMania I feel it also gave WrestleMania more of a mystique with all his victories...and that also ended when they killed Undertaker's WrestleMania mystique.
I don’t even remember Wrestlemanias by their numbers anymore. The first 15 or so I can recall every main event and major matches and moments. I saw this headline and had to click just to be reminded what happened at WM30. Am I the only one? I feel if you ask who main evented WM3, most people will tell you Hogan/Andre in a second. But if you ask who main evented WM29, a lot will go “which one was that?”
I agree with you for the most part.
There are a few WrestleManias that stick out in my mind, and I can remember the main events really clearly, and there are others that I just can't recall.
For me, the marquees are WM1, WM3, WM9 (for all the wrong reasons), WM10, WM14, WM15, WM17 - 24, WM30 and WM33. The rest are just a blur.