Now, exposing one more SET option can’t be bad, right? But Erland Sommarskog found out that this is checked by default. Now, using XACT_ABORT might now [sic] be a bad thing, au contraire. See this one of Erland’s series of error handle articles.
Making this change after all of these years is a little odd. Making it in a regular update is very odd. Using SET XACT_ABORT ON is a smart move in general, but there are times in which you don’t want to rollback immediately after an error; the problem is, are all of those places in your code well-documented?