How high is the security at the Disney hotels in 2016?

There's a guard station at the parking lot entrances. You need to be a guest (or have dinner reservations) to enter. I suspect it has more to do w/ people skipping out on parking fees and trying to use the transportation system for free, but it's also another level of security. Past that, you need a key to enter your room or the pool area.

security at the resorts is there but not in your face.

your magic band acts as your room key and at some resorts you are required to use it in order to enter the pool areas since non resort guests are not permitted to use the pools.

your magic band also accesses your tickets, fastpasses, dining credits, magical express bus for the way to the resort, and can be used to charge purchases to your room reservation.

Magic bands are your room key, photo pass, credit card, park ticket and they also are connected to reservations such as resort and dining. That being said the tech grows constantly on them and they are working more and more to advance them. Some rides now as you pass by can read who you are and send ride photos or list your name on a sign.

With security it varies from resort to resort.

For those that are not in a location you can walk to there is a guard station you have to pass, be it on a Disney bus or personal vehicle. Since they allow anyone to dine at any of the resorts it is not terribly complicated to get in. While you are welcome to walk around, dine or shop at any of the resorts you are not permitted to use the pool. Of course it is not under lock and key and hard to monitor, they will not be kind if you are caught.

For those resorts that are in walking distance or are easy to access (such as those on the boardwalk) it is a bit different. Last time we ate at Beaches and Creme we noticed that resort guests had to wear an extra band to get access to the pool and there was someone checking at the gate. I would imagine now that magic bands are used more and more though to gain access to pool areas on such resorts though.

In short, anyone can access a Disney resort, but if you are caught using things you should not (pool) they will take action.