I am also in Vine, and I don't think I am more generous to the free products that I get. In fact, it is sometimes the opposite, as Vine almost by definition provides things you don't really want, and I'm less likely to give a strong review to something I don't really want.
Membership in Vine makes me sensitive to the number of reviews each item on Amazon has, and I have recently noticed that the average number has increased dramatically. It used to be than an obscure or expensive item had 2-3 reviews. Now, virtually every item I look at has hundreds of reviews. Yesterday I called up a newly released $2500 camera lens to find that it already had almost 100 reviews. It feels odd to me, and I suspect that there may be astroturfing taking place on a massive scale, but I have no way to prove it.
You ignore the fact that they earned income on it in the meantime. Revenue in 2008 was $900 million (I don't know what the profit was). I believe that News Corp's investment in MySpace may have been quite profitable, even if they had only a stub left at the end.
Kodachrome is hard film to use; I gave up trying to take indoor photos with it years ago. I have continued to use it (about 25 rolls in the last two years), mostly because the quality of the images is obviously different from modern film or digital, and evokes nostalgia in older viewers. And I liked the bragging rights. It's no surprise that Kodachrome is gone; Kodak had been phasing it out for years -- first killing the larger format versions, then the iso25 and iso200 variants, and the motion picture film. The economics just weren't there; virtually every other color film uses identical (C41 or E6) processing chemicals, and Kodachrome used a different and apparently more toxic set. Without scale, it was more expensive to buy and process than other color films, and the emulsion can't even be scanned by most slide scanners. You're left with only nostalgia and archival properties to drive sales, enough for a small specialty chemical company perhaps, but not for Kodak.
"Don't think; let the machine do it for you!" -- E. C. Berkeley