I could also title this "Why did it take me 17 years to realize this?"
On my first couple of caminos, I wore hiking boots that were probably too small for my feet. Rookie mistake. That led to overheated feet, blisters, lots of unhappy feet while pounding the pavement. One year, my choice was to try something new in León or stop walking. I bought a low Salomon hiking shoe and continued on the Salvador/Primitivo pain free. From then until last year, I wore Salomons. No blisters, but terrible corns between the toes. My dermatologist said that the solution was to get a wide toe box, and Altras are wider than them all.
So I went to Altras for the wide toe box and then had an epiphany. Altras are trail runners, they are not hiking boots or hiking shoes. That means they are "less shoe" and more cushion. The Camino is not a hike in the outdoor sense of the word, it is a long walk with some occasional rough terrain. Trail runners are the perfect shoe for that endeavor. They have enough grip and form to keep you steady when the off-road gets rough (especially if you have poles), but their comfort on the asphalt and gravel just blew me away.
I am no expert in shoes, but I would certainly encourage everyone to search out trail runners. Altras are one brand, and every major outdoor shoe company has some. But it seems to me, especially as the caminos become more and more paved over, that hiking boots and hiking shoes are just way too much shoe for the camino.
Though the pain of past caminos, like the pain of child birth, always fades with the years, I was continually happy this year to see that at the end of long days, some up in the 40s, I never had that urge to yank off my shoes and free my feet. My feet may have been tired, like the rest of me, but they were not sore, weary, pounding, or any of those things.
Bottom line -- try the trail runner option. Its one drawback may be lack of waterproofing, but I have always found that my feet are wet at the end of a rain that lasts more than an hour anyway, goretex or not. I had only one rain on my 32 days on the Mozárabe, if you can believe it, but I found that the shoes dried very quickly.
I know there are others on the forum with far more expertise in shoes, and they may be able to point out flaws in my thinking. But this year, as every year, I saw so many people with boots or hiking shoes who were really having problems, and I felt so lucky with my trail runners. I am a convert! I will try not to proselytize though.
Buen camino, Laurie