Psh, Black/White 2 got shafted the moment X/Y got released. They got the short end of the stick for almost everything - Dream World, events, even time spent online. This is nothing new, no pun intended.
That said, I'm not sure why people are reading into this as something unfair.
Remember when the Global Link went down from Gen 5 and they were steadily phasing it out? (I know I'm the only one who actually cared about the Dream World, but bear with me for a bit.) They let us know well in advance that the GL was going to steadily transfer over to Gen 6. Thing is, the GL isn't run for free - a group of people have to create it, maintain it, work out all the bugs...honestly, it wouldn't surprise me if GL maintenance was a full-time job and I have a lot of respect for all the people who made it happen.
Leaving the GL up for Gen 5, although nice, would be devoting resources to something older, and they probably didn't have (and still don't have) the resources to properly maintain the GL for both Gens 5 and 6. I definitely miss the GL for Gen 5, but I don't blame them. At the very least, they told us what they were doing and when it would happen. We had a lot of advance notice, despite BW2 getting utterly shafted because of it, since it was so new. (The honest truth of that is that it honestly isn't BW2's fault; it just came out very recently and didn't have as much time to take advantage of it all like BW1 did.)
Nintendo Wi-Fi Connection is the same way - heck, Nintendo announced this on their own website
back in February
(I know the timestamp says May, but the article first appeared back in February), along with a full list of games that would lose WFC access at the time. Guess what I did? I booted up Dragon Quest IX and mooched off its Wi-Fi DLC system for all it was worth. (And, thankfully, I was able to get one of the Wi-Fi exclusive items only a few weeks before to finish a quest, so I got closure!)
But WFC, like the GL, is an old system that requires a lot of work to help maintain. With 3DS and Wii U both in full swing now, Nintendo is concentrating on their newest consoles - WFC is costly both financially and in the amount of people it takes to keep going. Granted, we've had a lot of great times with the DS and Wii in the past - we can say we've had a full run, can't we? Sure I'll miss it, but I got what I needed out of it, and I regret nothing. I had fun.
I'm mostly surprised they had WFC last for as long as it did, but I am pleased that it did. For someone that's been using it since 2007, it was a wonderful innovation and something amazing to have. And I think we can say, after all those years, it had a good run.
It's been great, WFC. We'll miss you. Goodbye, old friend. *salutes*