I'm sitting on a lot of miles, but I'm also looking forward to retirement not too far down the road with vastly reduced opportunities to go somewhere on someone else's nickel (or even deduct the cost of trips I pay for myself from taxable income). I don't expect things to change dramatically enough in the near, if not immediate, future to make this the wrong thing for me to do. I use some miles for high-value awards, "burning" in excess of 100,000 miles a year, but fly enough to build up my balance despite that.

So, in my case I think some "hoarding" makes sense, though it may not for many others. As with so many other things, in travel and out, it depends on one's specific situation. It's a bad idea to pontificate about how one answer, no matter how thoroughly someone thought it out for his or her own situation, is right for everyone.