Hi dmg. Your post raises an interesting question, that has very little to do with the quality of the extra songs.
What should any keen fan do when the artist he follows disappoints him with his work? And taking into account the fact that the cunning record companies put out so many editions with extras that targeting this very fan.
In a way there is only one answer: don't buy.
A second one that might convince with logic is : the keen fan would be satisfied even with these songs, because he can find thrill in the rarity, uniqueness of the songs plus if he is willing to pay this kind of money, he surely gets his rocks off simply by the distinctive sound of his voice and guitar. And you wouldn't expect MK to put as an extra a new song that is as good as SOS or ToL. That would have to be included in the regular release.
But since I feel the way you do, I do believe that there is something fishy with the whole collectible things that have been in circulation from the late 90ies. The fans are the sure cows to milk, so the companies create such "collectibles" that the vast number of them show that are not collectibles at all. And let me tell you, that the fetish thing that creates the whole demand, is an irrational thing ("I have it you don't have it, so that proves I am a better fan" kind of thing), because what would you do with a pair of dice and some chips? Three years after and you can still find Get Lucky box in almost have the original asking price. But it is a desire to own something that proves you are a good fan. And the companies exploit this desire. The logic thing would be not to buy and force the companies to sell the real product, the music contained, at affordable prices. Unfortunately, MK is a worldwide phenomenon and such sizes are helped by big companies and their routines. Bob Dylan, Bruce Springsteen, Metallica, Rammstein, Jimi Hendrix White Stripes, Stone Roses, Portishead and many others have done the same thing. Who's to blame?