I guess it really depends on your vape style. Sure, if I'm tootling at 10 to 15W, my single battery mods are fine all day. If I occasionally pull out some of my other tanks like a Crius or Limitless, I am going to be up around 35-50W. My single battery mod could handle that so long as I have extra batteries, but I would rather use larger mods so I don't have to really pay attention to charge level.
Yes, the market has been pushing higher and higher power with each new generations of products. Much the same as tank manufacturers turn out far more new subohm cloud tanks than the nice, simple low power tootling flavor tanks. I don't really like that, and would rather have a wide assortment to choose from, but just as the manufacturers keep the power wars going, vapers seem to support it by purchasing the stuff. Do those vapers need it? In all likelihood no. But I can't place all the blame on the mod designers because if there was no market, they wouldn't be making them.