Why would I want to play as a pig? Or a creeper for that matter..... In single player all you would do is walk around....
Why do you need a bigger crafting table for those ugly potions?
How can people like this?
Sounds like a great idea for multiplayer games, but I would just ditch the potions and chose to be a mob from the start.
Also, why do you capitalize every word in your sentence? Do you just like Kanaya from Homestuck?
this would be best as a plugin for a server where you start as a chosen mob and can do most things as a player except craft weapons but you can see your self (a npc with your skin) who's there as long as your on the server and does stuff like mine and buld to a certain limit but will be in beds if they have them then you can do break ins and take out other players.
Play as a different mob, are, are, are you serious? The game is meant to be played as a Steve, what purpose would it serve to the game, other then "Hurr, I'm a creeper, watch me blow myself up". And imagine how that would look on SMP, turning into a creeper to explode other's work, or a blaze to set their home on fire etc.
Your reason to add this is "for fun". Son, a lot of things would be "fun" to have in the game, guns, skyships, invincibility armour and so on, but that doesn't mean they are a good idea and should be placed in the game to server no actual gameplay wise purpose but it being "fun" to be another mob.
So yeah, this suggestion is just terrible, sorry, I do not support it.