The weight/size of the shorter focal length lenses should not be a big factor.
I thought I would like to see if I could check out the above statement. I therefore looked at the 12-35mm f2.8 pana lens, which is a relatively heavy m4/3 lens: 305g, 74mm long.
Nikon FX 24-85mm f/2.8-4D IF is a somewhat similar lens even though it is not constant f: 545 g, 83mm
Nikon FX 28-70mm f/2.8 ED-IF is probably a more fair comparison given that it is the constant f2.8: 935g, 122 mm long.
For DX, I could not find a single fast lens with a comparable range. I did find 18-55mm f/3.5-5.6G VR II: 195g, 66mm -- however the fair comparison for Panasonic would be something like 14-42mm F3.5-5.6 II ASPH Mega OIS: 110g, 49mm.
In conclusion, from almost 2x to 3x the weight when comparing smaller nikon lenses to comparable reach pana lenses.