We take our laptop everywhere and always leave plugged into the charger on the desk. I would not worry about it, espically at WDW. Over the years and many many trips to WDW, I have left so many different things out forgetting to lock them in the safe. On a few occasions I have left my 4 ct engagement ring on the dresser (not on purpose), and found it exactly where I left it.
We travel with all kinds of expensive stuff, digital cameras,cell phones, laptop, watches and jewelery. While we do lock up the jewelery and cash in the safe, we do leave the electronics out. Never had a problem.
I would be more worried about theft of information from using a wireless hotspot, than the theft of a laptop in your room. We have our own wireless service as it is secure, rather than sharing which leaves your info open for theft.