So terroir doesn’t effect these other traits?
The region, and even down to a particular microclimate within a region will affect how a particular variety may perform. Some perform very consistently across many areas, but when talking about Centennial, one grower from Oregon mentioned a condition called 'sleepy hop syndrome' that's brought about by relatively mild winters which doesn't allow the plants to completely 'reset' and causes really sporatic emergence come spring. This can cause issues with cutback as some crowns will be getting cut at the appropriate time while some may be getting cut early or late - resulting in less than optimal yield.
In the Yakima Valley, a farm that recently brought some acreage back into production up in the northern most point (Wenas Valley) claims that the area is absolutely ideal for growing Centennials.
When it comes to diseases, susceptibility/resistance is on kind of on a sliding scale from variety to variety so this is were the overall climate of a region comes into play in a big way. Downy mildew is something that thrives under high moisture/humidity so growers in places with relatively regular rainfall during the growing season (Willamette Valley, Midwest, Northeast) have additional fungicide costs built into their budgets. Conversely, the Yakima Valley only gets about 6-8 inches of natural precipitation yearly and may not have a control product for DM plugged into their program. If they get some unusually rainy spells during the season, they will incur additional costs for fungicide and HOPE they can react in a timely manner to make sure they can keep the disease in check so is doesn't negatively affect the quality of the crop.
The big issue with most varieties is that until about 5-10 years ago, none of them were trialed anywhere but WA, OR and ID before their release. The more places they're tested all adds to the cost and time it takes to bring them to market and is part of the issue with other regions having a hard time starting any sort of meaningful acreage outside of the 3 main states.
I realized in the early-mid 90's that there was a big difference in the character of some commercial hops I was used to that were grown out west compared to those I grew in Ohio, especially Chinook. Now that there are a few states like MI and NY with more than a few hundred acres planted, I always thought about those few hundred varieties that are kept out at the National Clonal Germplasm Repository in Corvallis. The descriptors of growth/vigor/aroma/etc on file are based on those hops as they were grown and harvested out west. What if someone had the resources to grow these varieties and do some quality lab work on the oil chemistry they produce in MI and NY to see what surprises they may reveal? I suggested this idea to Mallett from Bell's at a hop conference in MI a few years ago but don't know if he did anything with the idea?
As time goes on and our society gets farther and farther away from Agriculture, the general population has a harder time seeing what goes on behind the scenes with plant science. Hope some of this makes sense.