These values per mile are much much higher than what I would rate them.

For instance, KL/AF Flying Blue. I try to fly business class whenever I can. Roundtrips within Europe are usually between 350 and 500 euro all-in. Lets assume the 'best case' scenario where one-way flights in Business are 20K miles with FB, 30 euro taxes one-way, and you will be missing out on about 4K miles (~40 euro value). That means that the 40K miles needed for a roundtrip equal a value of (500-30-30-40) 400 Euro, or, exactly 1 cent per mile.

It's very tempting to look at a transcontinental first class award for 150K miles and compare that to its cash price of 8000 euro. While that would be about 5 cents per mile value, that only holds true if you would otherwise have booked the 8000 euro cash fare. If otherwise you'd have booked a 2000 euro Business class fare, you'd again be looking at about a 1 cent per mile value. Even if you would then fly in that First class seat. The money saved was 2000 euro, not 8000, so thats the actual value of the mile. At least that's how I look at it.

Having said (all of) that, 0.5 cent per mile is abysmal. Much too low for a 'regular' award flight. However it is reasonably on-par compared to other cash+miles offerings. Most airlines use a very low mile value for these cash+miles offers.

Update:
For example, Lufthansa offers the same 0.5 cent per mile value when doing cash+miles bookings. Details here.