It's not just touring bikes. People buy bikes of all makes and models all the time and upgrade parts. Bike manufacturers build bikes with the cheapest parts possible. Not necessarily bad parts, but parts they can get in bulk and make a bike to get it on the market. I prefer frame up builds done by moi. It take me a while, but in the end, I have a bike built with parts I like (can be a slow process). It's not for everybody though. Most just buy a bike, discover they need to upgrade and do it. Doesn't matter if its a $5000, HiPo Carbon Fiber racing bike, or a $500 commuter bike. Upgrades happen. Everybody has their own tastes and flavor their bikes accordingly.