Assalemu alaikom,
The advances in technology, and in particular information and communications technology, these days is, as one of you said, a double-edged sword. If not for the internet, we wouldn't be here on TTI, which is a valuable source of information on Islam, and a haven for people like me who are rather isolated from sincere folks committed to telling the truth about Islam. Yet, there are thousands and millions if websites, which are dangerous.
As for Facebook, I do have an account. It's a way of expressing opinions and sharing ideas. My "friends" are either family or colleagues at work, and I am a member of groups which are either associated with my profession (English Language Teaching) or Islamic groups. It's possible to make yourself "invisible" to people who are not on your friend list, and when you receive a friend request, don't accept unless you're sure of who they are. This is how I keep my account "clean". Although I do agree it's important not to let leisure activities get in the way of acts of worship.
Anything in life can be good or bad for us.....imagine even drinking too much water can kill.....and who would think water could be bad for you?????
Everything in moderation, and within the limits of Halal, is what I say. Wallahu aalem.