Many people find spelling unimportant. And if they do find it important, they sometimes still believe there is no need to learn to spell correctly since we have a spelling checker. Therefore, let me illustrate the flaws of this useful spelling checker tool, as in the poem below:
I have a spelling checker.
It came with my pea sea.
It plane lee marks four my revue
Miss steaks aye can knot sea.Eye ran this poem threw it,
Your sure reel glad two no.
Its vary polished in it’s weigh.
My checker tolled me sew.A checker is a bless sing,
It freeze yew lodes of thyme.
It helps me right awl stiles two reed,
And aides me when I rime.Each frays come posed up on my screen
eye trussed too bee a joule.
The checker pours o’er every word
To cheque sum spelling rule.Bee fore a veiling checker’s Hour
spelling mite decline,
And if we’re lacks oar have a laps,
We wood bee maid too wine.Butt now bee cause my spelling
Is checked with such grate flair,
Their are no fault’s with in my cite,
Of nun eye am a ware.Now spelling does knot phase me,
It does knot bring a tier.
My pay purrs awl due glad den
With wrapped word’s fare as hear.To rite with care is quite a feet
Of witch won should be proud,
And wee mussed dew the best wee can,
Sew flaw’s are knot aloud.Sow ewe can sea why aye dew prays,
Such soft wear four pea seas,
And why eye brake in two averse
Buy righting too pleas.

From: blog.darrencannell.com.
Spelling is indeed important. Firstly, to avoid confusion in meaning. Secondly, bad spelling may suggest that if the author does not seem to care enough about what he/she is saying, people should not be bothered to even read the article.
Until the time that spelling checkers will understand pragmatics fully, students need to be taught how to spell correctly, and, for example, learn the difference between their, they’re and there, to mention one of many pitfalls.