Does spelling, grammar and punctuation really matter?

“More choice, less calories.”
So says the advertisement for Coca-Cola™ that ran in the Sunday newspaper I read last weekend. Having just typed it, I can see that not only does it look poor grammar to me, but Microsoft Word doesn’t like it either.
I’m guessing that for this headline to appear in an advertisement for one of the leading global brands, it has passed through some pretty senior folk in advertising agencies as well as in the brand marketing team. Perhaps it’s a ‘deliberate mistake’ and like Captain Mainwaring in Dad’s Army they are waiting to see who will be the first to spot it.
After I recovered from the surprise and stopped trying to imagine how the advertisement had been approved, I started to think about whether it really matters or not.
On one hand, I understood the point the ad was trying to make and whilst not for the right reasons, I have certainly remembered the ad better than probably any print ad for a cola product for a very long time, if not ever.
On the other hand, as someone with two school teacher parents, taught grammar at primary school and lucky enough to work with some great copywriters in my early career; I do care about such things. On a rational level, a grammatical mistake (deliberate or not) isn’t likely to make their drinks any less enjoyable for me, but in the murky world of brand value and imagery, I think my perception of Coca-Cola™ has taken a small knock.
I accept that there will be plenty of people who didn’t notice or did notice but don’t care, but would they have minded if it had been grammatically correct?
I suppose my conclusion is that whilst I don’t want to suggest we become slaves to perfection, for some of our audience correct use of the language may be important and it probably doesn’t hurt to try to get it right.
I’m just going to run a grammar and spelling check now!