It took the disgraceful Panasonic almost a full 15 (since the introduction of the GH1) years to introduce what others had for a long time.
And most importantly, the weight of the Panasonic camera of all these series has increased monstrously. GH2 (which also had a multisensor, which was later abandoned) weighed a little more than 400g, and all the new monsters weigh 700g. What is the point of the MFT system now, if the camera weighs almost the same as a camera + optical lens with a zoom weighed before?
And by the way, Panasonic optics for MFT are not of particular quality - the resource of the lens mechanics is too low - 20-25k focusing in reality. Maybe it will be better with phase sensors, but with contrast sensors everything was exactly like that. And it was extremely difficult to shoot the video. I had to turn off automatic contrast focusing all the time and constantly press refocus while recording video in order to catch the desired focus, which additionally reduced the lens resource to rubbish many times faster...