Most patterns tell you to knit the length for X inches, not rows so you don't have to worry so much about the row gauge. Even where you do armhole shaping on every other row or so, that won't matter too much if your rows measure less. And one thing about swatches for larger garments... when you knit the actual item, the weight of it (since it's so much larger than the swatch) will pull the rows lenghtwise so you might just get row gauge too once it's knit.
I'm convinced that the reason so few knitters get both row and stitch gauge is that the designer measured gauge on the finished garment, not on a teeny swatch. So the row gauge is stretched out.