I wonder wether the weight gain is based on the glas or the body.
Both.
In the micro-4/3 system, there have been several "pro" level lenses released in the last 5-10 years. These tend to be both physically larger (to let in more light and allow faster fixed apertures) and all-metal construction. More actual glass, metal body that is physically larger = lens weighs substantially more than an equivalent focal length "kit" lens.
But to be fair they are still lighter and smaller than their full-frame equivalents. I recently got rid of my APS-C Nikon gear in favor of Olympus m43 system mainly because of this. Those 24-79 2.8 and 70-200 2.8 were beasts.
Absolutely. I was only attempting to address the upward trend line in the mirrorless (micro-4/3 specifically) graphs in the linked article.
I too sold my Canon DSLR kit for Olympus. I rarely carried the Canon stuff because it was bulky. But, I still wanted a bit more flexibility than the compact 1" sensor offerings.
Both.
In the micro-4/3 system, there have been several "pro" level lenses released in the last 5-10 years. These tend to be both physically larger (to let in more light and allow faster fixed apertures) and all-metal construction. More actual glass, metal body that is physically larger = lens weighs substantially more than an equivalent focal length "kit" lens.