It's a misguided analysis. Whether using miles for a ticket is "good value" or not is relative to how much it would cost to pay for the same ticket, not relative to the usual amount of miles it requires. Choices are always "poor value": 1 cent per mile. Your analysis ignores the basic fact: if you can get a ticket to Hawaii for 25,000 choices (just to fix some number), then you can buy that ticket for $250.

Keep your miles for when the price of the ticket is relatively expensive. It doesn't have to be an F award on SQ. It may be an economy domestic 25K award to a small destination for which the airlines charge extortion fares. It may be even a short-haul award when the price of the ticket is $400. It may be an upgrade on the PS service. There are plenty of options besides premium transatlantic awards on other carriers.

Or, since you mention the issue of flexibility, it may be a standard award on a premium cabin - wholly flexible and without capacity restrictions (almost really, since cancelling or changing routing would incur a $100 fee for non-1Ks). Granted, that's a lot of miles, but it's also comparable to buying full fare, so there's no question than the return is over 4 cents per mile.

You also don't have to take a trip just to get a high value for your miles. Just wait for the opportunity, and you'll get a good return for your miles for exactly the trip you needed/wanted to take.

I once had to get a ticket to GIG at the last minute and fares were over $2000, so I redeemed an 80K standard award (It's 100K now ). Not awesome value, but much better than choices, and at the time I didn't have the $2000 anyway (however most people have the $250 for the ticket to Hawaii).

That's just my two cents .