Do AFF'ers think now is a good time for our friends to start buying miles Yes/No
I would open accounts with everything under the sun: LifeMiles, Alaska, United, BA/Avios, US, American etc.
Then they're sitting there when they want to decide to travel/buy for a future trip(s).
Whether it's a good time or not? I'm hesitant with US given recent devaluations and the strong likelihood that there will be more to come, however it's more so because I don't really have the money to spend on it right now so I wouldn't want to stretch with such risk. If I had cash burning a hole in my pocket, though, I would have bought.
Just remember, points are a currency that can be devalued at any time and certainly do not appreciate. They don't earn interest, are generally non-transferrable and you are at the mercy of draconian T&C's. Your friends need to know exactly what they are getting themselves into along with the possible rewards for creative use.