Hysteria was an honest overlook on their part, I'm sure. Something as obscure as Tiller OTK could only be mistakenly conceived, not by intent, and for a brief period of time at that before it gets nullified or corrected which is exactly what they did.
This card is a specific, class card that was designed to be used to mana cheat. It's intention was/is to use it in conjunction with a specific set of cards (mostly class cards that have proven track records of success, cards that have been seeing play for the longest time) to allow infinite mana-cheat and very fast comboes. They must have been at least somewhat aware of the potential (trouble) that it holds, so they dumbed it down on the animation side of it, making it painfully slow to pilot it and difficult to successfully pull comboes with. At least that's what I inferred from it. Game's old and the code is spaghetti. In a game where spreading plague's dreadful long animation still exists, you stop questioning whether something was intentional or not. It just validates their laziness and incompetence.
Surprise fucking mechanics; it wasn't imbalanced, it's that other cards were just not as good. Oh and "it's in the name, WILD! Go WILD! Don't you like imbalanced game mode with WILD possibilities and infinite variety?" Heck of a lot of variety, indeed. Been playing wild for years and all of my successful legend climbs were done with hyper fast aggro or OTK decks.