Agree that there is too much Cosmere in WoR. The amount in tWoK was fine and adds color, with just Wit, the epigraph, and some interludes, but with more and more "world hoppers" interacting directly with the main characters and major side characters theorized/confirmed to be "world hoppers" it's getting to be very distracting to the series.
Edonidd's point is very valid in that the reader is starting to be forced to either read very shallowly or to be well-versed in the Cosmere. That there is a continuum of depth the reader can choose is false. As Edonidd mentions, this applies not just to new mysterious characters but to any mysterious objects as well.
For example, Moogle mentions that Gavilar's dark gem is unconfirmed and that Cosmere knowledge doesn't help here. But this is only from the point of view of a reader who is aware of Cosmere knowledge. What if Mistborn had a gem of the exact description with some unique magical properties? How would I know if I had not read Mistborn? How would I know that any of Marize's artifacts is from another series or something related to SA, or both?
The answer partly lies in boundaries. If Cosmere artifacts were only witnessed in passing, as true Easter Eggs, and is unimportant to the story, then the reader can "safely" ignore the Cosmere. e.g. The Dark Gem is given prominence, therefore it is not an Easter Egg, therefore I can speculate about it without needing Cosmere knowledge.
However as this boundary breaks down, such as with Nightblood, then this chain of thought no longer holds. The next time Sanderson introduces mysterious object, I will be forced to consider Cosmere influences regardless of the prominence of the object, and if I were not well-versed in Cosmere, I would probably just give up thinking entirely or catch up on Cosmere. This deprives the middle-ground of thoughtful, analytical reading without Cosmere knowledge.
This clearly goes beyond just rewarding the Cosmere readers (which I am), but is in fact punishing non-Cosmere readers who would like to go a little deeper without having to read all the other series.
The next boundary past the "significance of object/character" is capabilities and actions. If more characters (outside of Wit) start using magic from other worlds, or are implied to use magic from other worlds, then the book will start to have a arbitrariness for non-Cosmere readers. With Sanderson's magic theory, this will mean that the magic system becomes more "wonderous" and less "well-defined". This will split the readership and will be worse for non-Cosmere readers since the author will designed the book primarily around the Cosmere interpretation.
In any case, adding extraneous information is clearly sub-optimal for non-Cosmere readers. This distortion is very small when it's just passing Easter Eggs but becomes greater and greater as more and more Easter Eggs and important artifacts / prophecies / characters are added. I don't think it's that bad yet, but I think it's past the optimal point. Nightblade is already very troubling. And with the series being 10 books long, I think it will only get worse unless there is a deliberate correction.
As an aside, from an artistic / story telling point of view, I also feel it's distracting and beginning to subtract from the series even for a Cosmere reader. Though this is of course subjective and depending on what your tastes and what you think good story telling should be. Even Sanderson himself admits that this is an indulgence of his when he commented on the Emperor's Soul. I hope that he shows further discipline in this regard in the future of this yet-young series.
As a disclaimer, it's perfectly within the author's right to explore the Cosmere and reward Cosmere readers / encourage non-Cosmere readers to explore his other series. After all, this is the author's "baby" and he can choose to have it interact with its "siblings" however much or little as he wants. But to claim there are no adverse effects is disingenuous and I think the bad already outweighs the good.
