candy stripers laptop bag stitch pattern question

[leesespieces]

okay, i really don't like to knit, i prefer to crochet, but this bag is the perfect size for my laptop, and that stitch pattern makes no sense to me. does it come out the same size if you just do it in stockinette? is that stitch pattern really necessary??

[Saeros]

I'm not an expert on stitches but in my opinion it probably makes the side stronger so it can hold the weight of a laptop.