Experts and BHG readers answer.
Run-off and erosion
Just as the soil can't withstand being pummeled by the rain, plants won't either. If it were me, I'd rant and shame the builder into putting up a gutter. I'm concerned that without a gutter you'll always have mud spatter on your home. And if you have a basement, you've got the potential for water damage around the foundation. If a gutter is out of the question, you might try running a line of landscape stone or basketball-sized boulders along the dripline. The rocks will at least break the falling water and you could plant on either side of the rock.