I certainly don't think the Dalish adopted a nomadic lifestyle because it seemed easier or more healthy than living in one place. The main reason they continue to live they way they do is because they value their independence and can choose how they live their lives. Where they aren't subject to bullying and harassment, such as in certain parts of Rivain, it is noticeable that they seem happy to set up a permanent settlement on the fringes of the main human city and interact with their neighbours peacefully. They probably still hunt and forage in the forest areas to supplement what they are able to grow or buy, thus likely giving them a better standard of living than the peasants who seem incapable of doing so but being in one place and being able to grow food as well as hunt for it, probably does seem preferable to constantly travelling around and trusting to the vagaries of local wildlife.
The original Dalish who inhabited the Dales after the Long Walk seemed to have built cities, towns and villages, just as the humans did. May be some of them were nomads from day one but on the whole I would imagine this only became their lifestyle after the fall of the Dales. Mind you, that does make me wonder how they came up with the whole design of the aravels since they don't strike me as very practical conveyances. However, in the Last Flight it is stated that these landships literally do fly through the trees and this is done by magic. It never occurred to me to think of them in such a way. I thought the sails was to give a bit of assistance to the halla pulling them, like land surfers and the reason they could be seen above the trees, was that the masts were so tall. So if the aravels are powered by magic, then presumably it is something specifically elven that harks back to an earlier era. (Or may be the author just got a bit carried away).