Because?
I don't get the big deal. The first was an HMV exclusive in the UK (HMV shipped worldwide more or less). This one will have different art and probably only have 1 disc and be a Zavvi exclusive (who also ship worldwide more or less).
Why should you care? I take it you have the HMV version, I do. It doesn't bother me in the slightest if there's another version coming or not. Have you never bought a second edition release? Were you against the UK versions of Inception, Blade Runner or 300? What about Play's Iron Man and Iron Man 2? I take it you won't be getting The Goonies as there's a first run version in Asia? Not interested in either of Zavvi's Star Trek's I assume.
It applies to every consumer product in today's market, be them supposedly limited or otherwise. Newer, cheaper, better (or worse) versions come along all the time. Universal, WB, Sony etc. don't care about anyone's desire to have a 'collectable steelbook', they care about making money and as such keeping people in work and helping grow the economy. They're not interested in the secondary market (which has been artificially created by scalpers) and so on. And why should they be?
I own my HMV Thor. I paid retail price and I got what I paid for. Anyone who buys the Zavvi version will get what they pay for.