Because Dimentio is the coolest character ever... here are some things about him from
www.mariowiki.com/Dimentio:
"Even when committing acts such as murder, manipulation, and abduction, Dimentio never flinches and continues to grin and tell sadistic jokes."
"Dimentio has a very dark personality and has been shown to be a very disturbing and intelligent character."
"His name appears to be a pun on "dementia", referring to his apparent insanity, and "dimension" the planes of existence which he can manipulate."
"His understanding of good and evil is what's right for him is good and what's bad for him is evil. Through the lens of this very slanted understanding of good and evil, Dimentio is able to justify his acts of murder and deception through this philosophy."
"The value of a person's life to Dimentio is measured solely on how useful they can be for him and not by how good or evil they are."
"While his explanations are often odd, they are also eerily logical and posses a certain truth to them, hidden within odd similes. He is able to observe others and see what their strengths are, as well as their weaknesses."
Also, some quotes by Dimentio himself:
"And so I arrive, like a sudden windstorm at a kindergarten picnic!"
"So very nice to meet you... and your mustache!"
"That sucking sound is your free will being plunged from the toilet of your mind!"
"Ah ha ha ha ha ha ha ha. Again, for dramatic effect! AH HA HA HA HA HA HA HA."
"And so I strike, like an unseen dodgeball in an echoing gymnasium!"
In fact, I like the character so much that my speech patterns have been heavily influenced by him, in addition to my username on almost every site.