You can go no gutter and be safe IF you are willing to put in the extra work:
Dig a trench about a foot wide and maybe 18 inches deep all around your house (skipping over paved driveways and such) centered under the edge of your eaves and fill it with gravel. Add a short stub leading out into the yard a few feet, ideally in a direction where the land slopes down away from your house.
The irregular surfaces of the gravel prevent any ‘coordinated’ backsplashing onto your walls and the falling water can’t damage grass that isn’t there.
During really gusty rainstorms a lot of the water may not land on the gravel, but in those cases it’s being blown around randomly enough to keep it from beating paths into your lawn.
BTW wide eaves are good for keeping the water well away from your house BUT if you live in areas visted by hurricanes they also offer great leverage to the wind. Good bye roof!
I live Melbourne in the great land downunder and have to admit that I have never seen a house without guttering down here. I believe in Queensland there is no point to guttering as the volume of water that falls during the wet season overwhealms the guttering and ends up pouring onto the ground anyway.
In my street, the houses on the high side drain into the street. This helps flush the street clean. From there it flows into the storm water drains placed every 100-200 meters down the street so the street doesn’t overflow. The houses on the low side drain directly into the storm water system.
The area that I live in is highly reactive clay. Substantial rain around the foundations during winter followed by endless days of summer would cause saturation followed by severe drying out. This causes the clay to expand and contract enough to cause severe damage to the foundation and structure of the house.
We have no trees planted near the house for the same reason. Substantial usage of the ground water by the trees dry out the soil. We are investigating trees that don’t require a great deal of water that we can use around the house, but at the moment the closest stand of trees is around 10-15m away.
In summer we also (very occassionally) water the foundation of the house. Not excessively, but enough (we hope) to keep the soil from contracting substantially due to the loss of moisture.
In addition to all of the advantages of rain gutters that have been cited there is at least one more. They quiet your wife if she wants them and you install them.
Like you, where I live I have never seen a house without gutters (except ones that are about to fall down anyway). With the rainfall here, which is about the same as Seattle’s, you want to make sure that what falls on the roof doesn’t end up under your house.
My sister lives in Cairns, Queensland and I’ve visited there often. As far as I could see, all the houses in the area have gutters.
One place I’ve been was notable for none of the houses except one having rain gutters. It was even pointed out by the tour bus driver when we did a short trip through the town. It’s Jabiru, the town in Kakadu National park in NT. Seasons there go from the dry to the wet, with not much in between. During the wet they get a fair amount of rain in a short time.
It might not seem like much, if you spread it over the year, probably about the same as at home, but when most comes in heavy rainfall or cyclones it would probably overwhelm normal guttering. The other side of the coin is that Jabiru has a fair number of trees with leaves that would love to block those gutters during the dry to cause lovely messes in the wet.
Of course, there are parts of NZ where you need something out of the odinary as far as guttering and drainage are concerned. How about Milford Sound where the average rainfall is about 6 metres a year! That’s nearly 20 feet.
When I lived in tropical West Africa the houses there did not have gutters. During the rainy season you could have an inch of rain in a quarter of an hour. No gutter is going to cope with that. What we did have were “storm drains” which are three-foot deep, concrete lined channels at the sides of the roads. I have seen those fill up and overflow in a heavy rain storm.