I really don't understand why one would need the street address for a waymark at all.
I like when the box is optional, I don't usually add the address, not because I'm lazy, but because I think it's redundant and a little silly. And if it's going to be required, the text box is much nicer than the individual fields.
This is a GPS game, right? You've got the coords, what do you need the address for? If you're planning to google the directions, OK, just type in the coords. If you're planning on tapping it into your turn-by-turn, OK, just type in the coords. Using the address so you know when "you're there"? Well, when you arive at the interesting/informative thing that you were looking for, you've made it. If you can't find that building/statue/monument/historical marker/trailhead/mcdonalds/whatever from the coords, is the address going to help you much?
Maybe I've missed some purpose of the address, but I just don't get it.