Great tip. Not accumulating large miles with one airline is important if you aren't diversified or don't travel a lot. It pigeon holes you. This is where transferable points - like Chase UR or Amex MR really come into play. They are naturally diverse and worth stockpiling.

If you KNOW you won't be traveling in the near future and your points will expire, it's better to spend them on something.

Remember too that airlines have partners. Etihad specifically partners with Air France, Air Canada, American Airlines, KLM, Jet Blue and many others. As such your points are much more diverse than it may seem at first glance.

What others may not realize is that almost all airlines only require SOME SORT of point exchange to re-up your miles for another 2 years (or whatever the point expiration for that airline is). That typically means simply spending miles on a purchase or buying a small amount of miles extends the expiration of all of your miles.

Using miles to buy gift cards such as you did can be a real option, though it's typically not the best use of miles as you'll typically get only $.01/mile at best out of that type of transaction. My goal is always to maximize those points through partners and diversification.