That is two totally different review sites which have mentioned it and I have seen it mentioned elsewhere. The 16MP jpegs apparently seem nicer out of the camera than the 24MP ones.
Remember a lot of people do shoot jpegs and the Fuji RAWs are not that well supported by many free RAW utilies let alone popular ones like Adobe ACR. Plus,cameras like the XT10,and XE2S will be replaced by newer bodies using the new sensor and these will be less orientated towards RAW shooters anyway.
You are also assuming that every person buying a Fuji mirrorless camera also has a calibrated desktop monitor or a more expensive laptop with a decent screen. From my own experience I would say that is not really the case.
For me this is a bit dissapointing,as I will probably be picking up an XT10 or XE2S for the family as a general purpose camera for when we visit places. The decent colour out of camera is one of the reasons we want one,and not having to fiddle in RAW all the time.
If their successors have mediocre colour instead of that "Fuji look" its going to push people away to other systems. Its less of an issue with XT2 and XPRO2,but more of an issue down the range.
Fuji needs to get it fixed pronto IMHO OFC.
The D600 will still be kept for situations where I really want the best IQ,and are willing to process each RAW picture. The irony of that is the D600 has some of the best jpeg quality I have seen out of any camera. However,even with light lenses its rather heavy.