I enjoyed the way it was done, but I think I understand your point too. Such a unique character, and that's the word, character.
The Undertaker story is pretty much a book that we all know - his brother set their house on fire killing their parents and apparently dying in the fire too. Undertaker, alone, was taken in by Paul Bearer, a caretaker and friend of his family. He eventually became Bearer's pride and joy of life by becoming a menacing fighter controlled only by the dark forces. In WWE he could cause pain on everyone else and he enjoyed it. It was a menacing person. A really dangerous individual, a lunatic to some. He eventually showed he had some kind of magic powers. He appeared out of nowhere, he could black out buildings and even throw lightning bolts at people. He won the championship by beating Hulk Hogan and he couldn't care less about the fans as in, he was the one that did it. Not for them but just because he could.
Some years later his presumed dead brother debuted too. He gave him an helluva beating and it was Paul Bearer again who revealed to be behind all of this. It doesn't matter of course that what Kane did was terrible. At the end of the day, they were brothers and Undertaker showed a lot of complex compassion. They eventually fought at WrestleMania. Undertaker formed a Ministry of Darkness. He hanged someone at WrestleMania. He even threw a dude from a 20ft cage, not once, but twice.
In 1999/2000 he quit the WWE. He wasn't so sure anymore if wrestling filled his void. He did some soul searching and he found IT. His lost soul that died when he was a kid and the fire consumed all the love he really had. He became the American Badass and he rolled with it for 3 years, until of course, his brother Kane finally 'killed him' again in a Burial Match.
Nope though, because even though he had a soul, he never truly lost his powers. But not being able to breathe under a pile of earth, killed his soul for good and he was once again The Deadman. Tragic, I know. It was the druids, a group of mistic individuals, who brought The Undertaker back. In this lore, they were the past Undertakers (read untilt he end)
He was god at this point, specially at WrestleMania. He beat everyone who tried to keep him down, but he was so resilient at that stage that people just assumed it was his dark magic taking special effect at the stage. Nothing and nobody could beat him. Randy Orton even set him on fire at one point and NO HARM DONE. He was basically immortal and the only way to beat him, was by stealing his magical urn that gave him powers or to just make sure you could just caught a fast 1,2,3 count. Don't you ever think on trying to submit him, because you would die first than hearing say the words "I Quit".
He beat legend after legend at WrestleMania, until one man, Brock Lesnar. A Beast. A Freak of Nature. He did what no one else could and his will was bigger than The Deadman's powers. He won again. He won again. He lost to the young stud named Roman Reigns.
Now what should've happened was - the druids should come out, and I am saying pretty much the entire roster dressed as druids. One of them would just show him the urn, broken in pieces. He would take the jacket, the gloves, the hat. He was no longer magic. He would look at the arena one last time and join the druids. He would then wear their cape and finally be lost in the hundreds of figures dressed the same way. Then there it was, one of them, raises his arm and we know it's The Undertaker.
We cry a lot and whisper: "don't go". The gong. The dark light. All of them, the 100 people or more, were gone.