Look at this way, these are consumables and if you want your system to perform at it's optimum level you need your parts to be in optimum condition. Look at what you spent on tobacco cigarettes each month and then look at the cost of a new atomizer every other month and 30ml of juice which one do you think is going to be cheaper? You could get a new kit each month and still come out ahead. Don't get it into your head that these are a one time expense with the exception of the juice because that is simply not the case.
I rotate between a few different models and atomizers in the models if they aren't the cartomizers which I have grown to prefer. I don't believe in cleaning them every time I have done it I don't like the way it performs after the cleaning or it dies so I don't bother with it, not at the price they are new, I just throw one in with the juice order and don't think twice about it.
Try to think of them as oil filters in your car, it's will run without changing the filter but eventually that filter is going to be filled with gunk and cease functioning right causing your engine to run for crap and ruin it eventually. The atomizers are the same way, you want them clean and fresh in order for your E-Cig to perform at it's top level.