Sure, you can live without it. But once you learn it you wont want to. It makes coding easier and more fun. Its the kind of stuff you code and then feel proud that you coded that way. It will limit the growth of your programming if you dont learn it though, as larger and more complex tasks become more of a headache (or perhaps impossible) without OOP.
To an extent the concepts are already used in flash. Just like you attach and manipulate a movieclip as an object (and perhaps put code inside that clip) so too OOP with classes follows the same pattern, except your code is in more manageable actionscript class files. It also eliminates use of the messy prototype method (though it compiles to the same thing).
Additionally, you will be stuck with AS 1.0-2.0 without OOP, as AS 3.0 relies a lot more on object oriented practices and even disallows some of the old sloppy practices.
If you enjoy coding, I recommend it. A person can live without a car as well, but life is not quite as enjoyable. OOP is one of those things that just makes coding easier :)