With all due respect, I think it is a lack of brain power to say that Kakashi's Susanoo or MS is an asspull. In the best case, if you claim to have brain power, then I believe you have been reading your own version of Naruto for years, and unfortunately, you are being in denial of the true series. The facts are clear and we know them: (1) Sharingan is the result of eruption of special chakra from the brain, (2) chakra can transmigrate from the world of the dead to the living world into someone, (3) two people can be connected through chakra and talk to each other has Obito and Naruto have done before, (4) It is a Naruto fact for someone to transfer a dojutsus to another person, and Sasuke was the first to be beneficiary of this principle from Hagoromo.
By the way, you forget Minato being dead and buried, yet appearing inside Naruto to perform a full-fledged Hakke fujin. You forget Kyuubi being in form of chakra inside Naruto and still using Naruto's body to give chakra to someone. Simply put, the fact you are citing shallowly are the basis of Naruto series, and they are actually the supporting argument for what happened in chapter 688.
So after these, you end up asking question and coming up with an uncertain answer. This is the actual proof of what I said earlier - that is you are ignorant of the true Naruto facts, or simply in denial of them. The answer to 688 is simple - that is Obito transfer all his Uchiha power to Kakashi through chakra transmigration. We have seen it with Naruto possessing Ashura's chakra, and Sasuke possessing Indra's. Both of them are themselves and do not have the mind of neither Ashura nor Indra. BZ even mentioned that they are very weird transmigrant because they cooperates.
FYI, if Uchiha DNA was able to give Sharingan, then Orochimaru would have Sharingan long time ago. It has been proven many times in the manga that the Uchiha power has nothing to do with DNA. Rather, it is a chakra erupted from their brain. So as far as Kishi is concerned, there is no contradiction.
The series has built a logic, and this logic is valid within it context. The earlier you will accept the logic of the series, the better the series will be.
PS: Do you guys still recall Madara using Susanoo without his eyes? It would help you a lot.