I'm not Catholic, so I don't know. Why would he do this?
It is extremely rare, but I think in today's age (media, rapid communication, etc.) he saw what PJPII slow demise did and he is trying to avoid it.
Remember, he was on his way to reading and praying in Germany before he was elected Pope. He had a front row seat to what JPII went through and likely is trying to avoid that spectacle where his "death pool" over shadows important papal work.
For those who are using this as an opportunity to slander the church or the Pope - i have some select words for you but out of christian charity will simply pray for you instead.