It does seem like a bit odd timing but the timing is never perfect... it would have been nice I guess to have an announcement a few months in advance and have everyone informed about the options and let people try with GMAT prep to see if they prefer one way or another - that would be more ideal BUT, it is a benefit they are rolling out, so complaining about something that is being improved and for free, is not in order.
Nobody has to prep for anything, you can take the GMAT the same way everyone has been taking it for 5 years, ever since the IR introduction. So technically, this is a minor item, but naturally many may try to take advantage of it and it may not be convenient for everyone, esp. those taking the GMAT soon, so they have to choose how much they care about this change.
One thing GMAC did mention on the call was that some people have clearly scored LOWER on the test, in part because they were coming in cold without AWA/IR to "warm" them up, so something to keep in mind as you devise your strategy!