That's nearly the only world map that size that shows Jeju-do.I beg to differ.
In the world map gallery of the blank map directory, on page 1 you can identify Tobago on Maps 4, 5, 6 (5 & 6 being one-pixel-white squares, admittedly), 7, 8, and 9. Jeju-do, by comparison, is only a few black pixels on 5 and 6, and appears in colorable form only in maps 7 and 8.
On Page 2 Tobago is visible in maps 2, 3, 6, 7, 8, and 9, maybe 4 and 5 but both of those are rather confusing. Jeju-do, by comparison, appears only on maps 2 and 5, with two not even showing it large enough for a single white pixel.
Page 3 provides the only map-type that shows Jeju-jo with white pixels on the standard world map (maps 2 & 6), while Tobago is visible and editible on maps 3, 4, 6, and maybe that's it on map 10 but I'm uncertain.
Page 4 is the only page where a majority of the maps provide visible and editable versions of Jeju-do, as they are all variants of the same island-filled map. Tobago is still visible on the other three (maps 4, 5, and 10) maps.
I will admit that the island-filled variant on the standard world map has been common on the past five or so pages of Map Thread V, but the island-less variant that does not show Jeju-do is used just as often, and the vast majority of other blank world maps available are more likely to provide a visible and editible version of Tobago than J-d.