Antarctic Termite said
We already have 'Ghosts' and 'Dragons', so it does fit in. I think the name is really the only thing a lot of people have against it, but I'm not fond of that argument, as Pokemon type names are rarely restricted to what the word is usually used to describe. A lichen is a 'bug' but a scorpion is not, a slimeball is a 'dragon' but Charizard is not, a jellyfish is a ghost but the god of nightmares is not, a bronze bell is 'steel'-typed but a turtle with giant steel cannons is not. They're elements that different species are attuned to, not biological families that species fall into.
Your argument is based around things that appear in first generation compared to the newest. A turtle with giant steel cannons is not steel type because it is based around water attacks. Charizard is not a dragon type because it is based around fire attacks. Also, they're starters. They can't be anything more than the main three elements. I call it bullshit because it is strong against Dragon type, but anything that isn't extremely wimpy can kick it's pink sparkly ass back to the pixie it plopped out of.