Yes but Obito is not Kakashi. He is a full blooded Uchiha. Kamui is his Sharingan Tech. Just as Kakashi's eye is Obito's as well. Obito can use kamui much better than kakashi. Even if kakashi need the Kyuubi to do it. Obito should be able to do it as well, especially now that he has the Juubi's chakra. Taking away someone's signature move just because they have a tail beast is lame anyway you slice it. As I said before. he should have just lost his other Sharingan to kakashi in their last fight. it would have been a good enough reason for him not to have Kamui as he would then only have had the Rinnegan.
This is merely a speculation but it might be explained simply by following the tails logic.
According to the manga the more tails a Bijuu has the stronger it is, this was proven when a half Kurama BM Naruto was able to stomp 6 Bijuus (2 tails to 7 tails). With that said we can easily speculate that Kurama chakra scale is above of that of Hachibi, hence why Kurama was able to lend Kakashi enough chakra to teleport the Hachibi.
(#A) Following the same logic Kurama would not be able to lend Kakashi enough chakra for him to teleport it(Kurama).
The same should be true to the Juubi, the larger the number of tails the more chakra it needs to transport, since the Juubi is ten tails we can imagine that it's scale of chakra levels is enormously superior to Kurama's, proven by recent chapters.
So following this simple logic it becomes pretty obvious that Kamui should not be able to allow Obito to transport himself and the Juubi to Kamui's Dimension.
Again I must say that I have to be prudent about this issue both because I'm not certain about my point #A and also I want to make sure the translation was an accurate one, because if Obito is still able to use Kamui I'd think it as legit, because being Sage of Six Paths must carry some perks!
Kakashi said himself he wouldn't have been able to do it otherwise.
