Originally Posted by DNA-1842
The problem with the name Sebastien is that it is of Greek origin, and Tolkien mentions in the Appendices that he specifically avoided names of Greek or Latin origin because in Middle Earth the equivalent of Greek and Latin influences come from Elvish. (He broke this rule for some Hobbit names, which were mentioned only in a diminutive form - but he did stuff like changing "Sam" from a shortening of the Hebraic "Samuel" to a shortening of the decidedly more Anglo-Saxon "Samwise".) Sorry, I nitpicked on your behalf.
That's a little more detailed than the criticisms I've read. On theonering.com's "list of changes" website, the criticism was that Sebastian seemed too contemporary. They acknowledged the fact that Tolkien used contemporary (rather fratboyish sounding) names for the Orcs, but said that Tolkien regretted that. My first response to that is, "Too bad." It's published.
But even if that's the case, the nitpicker's response would be: well at least the Orcs are more forgettable characters individually. Fair enough. But that doesn't exempt other characters of the books: Tom Bombadil, Rose (Rosie), Bill. And let's not forget the name Fatty.
Still even at that, those characters aren't exactly main characters, though (at least in the books) Tom's part is bigger. But it's not like they were the principles of the books. Imagine if one of the Nine were just named Jackson or Brian. The thing about Sebastian is that he's thankfully a very minor, forgettable character.