Choices and consequences the defining element to call a game an 'RPG'?... lol no.
There's been plenty of games that are most definitely rpg's and have close to none, or none, 'choices and consequences'.
Unless, the term is confusingly used to describe different gameplay mechanic approaches as well instead of the more commonly understood way to refer to 'choices and consequences', which is (involves) branching storylines and quests, different endings and the like (things that involve direct player choice instead of, let's say, 'character numbers' choice).
You don't simply play a role (or pretend to play one) you play (or rather can play) as many roles as the game mechanics allow you to. That is, it's the game mechanics that define it, the different approaches it offers for solving puzzles and quests to different character builds; for instance; you have a quest to retrieve a certain powerful artifact from a heavily guarded place, now depending on the stats and skills of each build, the retrieval can be approached in different ways; a thief-type may go in sneaking, assassinating silently, lockpicking, a warrior-type may fight it's way in and out, a mage-type may mind-control some guard or beast to get the job done, or levitate undetected past the walls, a diplomat-type may bribe or convince some unhappy guard to get the artifact for him, or to let him in through the back door at midnight, etc, etc. That would require that both the game mechanics and the gameworld itself are properly built for it, and that the approaches are as unique as the character build (by build i don't mean the archetypical thief, mage, etc, stuff that i used in my example above, but if you think of non-class systems such as the one in the Fallout games, i mean the general 'tendency' of the character as dictated by it's player-chosen stats and skills) required to do it (that is, character skill over player skill). That after you get the artifact you get the choice to give it to the npc who asked you for it or to tell him to bug off and keep the artifact for yourself (and perhaps make an enemy out of that npc or group), it's indeed a very, very nice thing to have (and one that it's considered a 'must' nowadays), but not the defining RPG seal.