But seriously...
This is all a matter of style choices. If I were to write a formal paper, I would certainly refrain from starting sentences with coordinating conjunctions. But why? Because it is not really considered proper grammar. Nor would it be to start a sentence with "because", unless you start with a subordinated clause followed by a "normal" clause within the same sentence.
But there are other venues, other style choices, other sets of rules. And sometimes you even omit an "and" that would be expected. For effect.
In informal language, eg such as used at a god-damned hockey message board, in poetry, in easy-to-read tabloids and in quick paced fiction, it would be quite normal to start sentences with "and", "but" and "because". And why? Because I say so.
No, actually because it allows for shorter sentences and emphasis. These things are of no importance in a formal paper, but can easily be more important than stodgy 19th century grammar preferences in these other arenas I mentioned.
In conclusion, there's really no universal right or wrong here; it all depends on the venue and the style choices of the writer.
In a similar spirit, when Gwen Stephanie (at least I I think it was her), made an updated version of "If I Were A Rich Man", she called it "If I Was A Rich Girl". Not because she did not know how to use a subjunctive, but because it would make the song sound more dated. Thus she went with the grammatically incorrect phrase that sounds more like how young people (and especially Americans) would express themselves. Just like the Beatles littered their songs with Americanisms that were probably not how these Scousers normally expressed themselves, neither in writing or speech. It just sounded cooler, more rock'n'roll. Or whatever.
It is all about style choices and venues.
But what do I know? It's not even my language.
