Well, Shakespeare was very fond of the double negative, and used it as an emphasiser of the force of negativity - and so do I, at times!
Think of Donne's play on - not double negatives, exactly - but the paradox of distilling from nothingness:
"A quintessence even from nothingness,
From dull privations, and lean emptiness ;
He ruin'd me, and I am re-begot
Of absence, darkness, death - things which are not."
(Nocturnal Upon St Lucy's Day" http://search.able2know.com/About/3711.html
Shall dull grammarians have us not, no never, write such things? Shall we part with paradox? Consign contradiction to the coffin? I think not!
But, bad grammar, with bad spelling (AND CAPITALS), follies and inconsistencies DO irritate me on fora, and I laugh at them whenever I can.
As to whether I think not following rules is good or poor writing, I cannot tell you - it depends upon the ambience of the particular post, and poster.
Picky? Indeed! Prolix, today? Indubitably!
And, some might say, overly fond of dashes.....and dots....