The absence of the final 'and' creates a more emotional tone. It is more poetic. Omitting the final conjunction creates or maintains a certain tension due to the final term not being telegraphed in advance by the 'and', which by convention signals the end of that kind of sequence.
The final 'and' guides the sentence down to a sense of landing or settling. When it's missing, the sentence stays 'up', partly because in its absence the final term is not known to be the final term until it is not followed by another term. It creates a sense of the sentence having ended prematurely, which causes the pause in between the last term and the sentence that immediately follows to be perceived differently -- if there is a following sentence, which there might not be, since it's a good place to end a paragraph/chapter/speech/etc. When spoken, that pause will likely be fractionally longer than otherwise, so the sentence can sink in, almost like letting an echo or reverb die out. It produces a different cadence. It's more dramatic, and can have an imploring quality, so it could sound silly or pretentious if used with a sequence that somehow doesn't deserve the pomp, the circumstance, the glorification. :)
I also think it's more difficult to achieve the effect with only 2 terms, because a third term is required to establish a sense of your being in a list, which is required to create a sense of a premature ending. It's because the ending feels premature that the sequence feels like it could continue. The sequence can be extended to 4 or more terms, but eventually you hit a point of diminishing returns. Though it all depends on the delivery.
A different but comparable effect can be created if instead of omitting the last 'and', you replace all of the commas with an 'and'.
It manipulates expectations.