I say ‘we’, because I wasn’t alone in spotting this comparatively recent trend. The estimable Tom Albrighton over on ABC Copywriting did all the heavy lifting back in May. Quick on his feet, that Tom. All I’m bringing to the table is a few more examples.
I’m talking about the ubiquity of the two words ‘that’s why’ in advertising copy. As Tom says, it follows the formula:
At A, we know how important B is. That’s why we C, which gives you D.
Or: You know this? That’s why we have this
It’s cropping up everywhere. It’s like every copywriter in town has been on the same course. Which would be strange, because copywriters don’t go on courses.
Here’s a few examples I’ve half-heartedly collected over the past two weeks. There are loads more out there.

'Find healthy'? Let's not go there.

One ad. Three that's-whys.

Oh, so that's why!

This is a bit of a non-sequitur, in my opinion.

Basically, we wanted to increase profits and hurt the competition. That's why we were compelled to make our products look and sound desirable. Otherwise we'd have just thrown together the first thing our designers came up with.

It's Sidney again, still looking for healthy. Hang on, wasn't he 88 in the previous ad? Time flies when you get old. (That's why you should try and enjoy every day as if it were your last.)
Cheerio!