Well, I'm not anyone official, but have been wondering about this, and am still looking - but as far as I can see, it's no good blaming Sony, it's Google who seem to have shifted a few goalposts.
They may be thinking the market's not big enough to worry about - and they're up against it anyway, with Amazon's hold on the market,established international e-suppliers, in UK Waterstones and Smiths'Kobo, etc..., as well as loads of other sites offering free/reduced price s tuff and advice on how to get it, the big free sources like Gutenberg.
And there is the Reader Store now, and Google may have thought it wasn't desperately good marketting to share a market, of any size, when times is hard.
If I hear anything more I'll post, but it looks like you should be moaning at Google.
And it is only another shop, after all - how many do we need ?