I'll spare you the details of why I've spent so much time learning about crawlspaces, moisture, and drainage over the past year, but let's just say this is something I've studied exhaustively myself. I've even had conversations with several experts (people in the home performance, HVAC, and drainage businesses) about issues involving wet crawlspaces. So I'm not as much of an authority as some, but I know a thing or three. Or four.
Bottom line: You don't want a wet crawlspace. It's a breeding ground for mold. Roaches and other creatures love when it's wet down there. I'm not sure if termites are an issue in Oregon, but they are where I live. They like a moist crawlspace, too. Wet wood = yum for termites. And if you've got equipment down there (ductwork?), the mold that grows in the crawl could grow inside that stuff as well.
Wet soil around a foundation can also lead to foundation problems... greater settlement than normal, sinking porches, etc. If the foundation walls stay wet, their structural integrity could be compromised, although this would have to be significant over a long period of time to be an issue. But you did say your house is 70+ years old, yeah?
Honestly, a sump pump is a bandaid solution for a wet crawlspace. A better approach is to stop the water from getting in there in the first place. Companies that specialize in exterior drainage are expensive, though. If I were you – and I'm assuming you're pretty handy – I'd get a drainage pro to design a stormwater collection/removal system for me. Maybe they could just explain what to do rather than actually design one. Then I'd build/create/install it myself. There is always a way to direct the water away from the structure... even when you're at the bottom of a hill. However, you might be renting a Bobcat and laying lots of pipe!
Another (less ideal, but not bad by any means) solution would be to install a better sump pump. A waterproofing company can probably figure out how to install a more heavy duty one even in your cramped crawlspace. Then when the crawlspace is dry-ish, you could install a vapor barrier on the floor and put a fan or two down there to keep air moving and prevent mold growth.