I agree that the language in these emails is quite misleading. Just received one as well.

The emails are also not clear on what changes are made to your itinerary so you have to check your original confirmation email and compare the flight times..

Anyway glad I read this thread, because I was about to click the " I want to cancel my flight and use my ticket later" button, and I would have hated having to call them to reinstate my booking..

I do find these emails are a bit sus... I had a really good price on my ticket, and the email states that I have to accept the changes by a certain date or risk cancellation. Perhaps there to provide an excuse for Lufthansa and for them to have the leeway to cancel low fares they later find out that they can sell at a much higher price?