I think that example's more a practicality of pronunciation. The two vowels in ce est are the same, and French runs the vowels together between words, so you'd end up pronouncing it the same either way.
That's not to say that you must always speak with perfect grammar all the time. You can play around with things for humour, character, rhetorical effect all day long.
That's not to say that you must always speak with perfect grammar all the time. You can play around with things for humour, character, rhetorical effect all day long.