Korean names are translated (romanized) into English in several different ways. A variant of McCune-Reischauer System ( https://en.wikipedia.org/wiki/McCune%E2%80%93Reischauer) was adopted by the South Korean government in 1984, and Revised Romanization ( https://en.wikipedia.org/wiki/Revised_Romanization_of_Korean) came into official use in 2000. However, neither of these systems became universally used, particularly on surnames (e.g. Kim (김), Lee (이), and Park (박)).
Sensei's Library (SL) had adopted the variant of McCune-Reischauer for Korean names thanks to the efforts of many editors in the past, especially John Fairbairn. In 2016, after the wide media coverage of AlphaGo vs. Lee Sedol match series, many new users started using SL as a Go information source. As many of these new users are not Korean or Go specialists, some editors started wondering if adherence to McCune-Reischauer is in the best interest of majority of the readers.
While the advocates for the change cited near-100% use of "Lee Sedol" by the recent (2016) articles on publications in English, and by Lee Sedol (and Myungwan Kim) himself, opposing opinions deem having a unified standard is more important and the changes violate the existing standard.
This was discussed on Coffee Machine in April 2016 and the following list of items were proposed:
1. Yi Se-tol article renamed to Lee Sedol. 2. Kim Myeong-wan article renamed to Kim Myungwan with the recognized possibility in the future to be renamed again to Myungwan Kim if he becomes an US citizen or permanent resident. 3. Following the romanization standard by go4go.net is suggested to be an alternative standard.
The above is for the record of what happened for the future reference described mostly from the point of view advocating the changes, and is in no way intended to be a description of SL policy or standard.
If you have opinions or issues, please feel free to state them in the "Discuss page" (forum) of this article. A general info on the consideration of what is inappropriate/harmful for SL is here.
DuEm6: It's unfortunate that there was no conclusion or even discussion about this. Nevertheless I think it's wise for wikipedia contributors and other players' database not to use the modified/variant MR used by SL. Anyways Korean romanization is a mess.