In the age of datamining, where versions are compared and contrasted by hundreds if not thousands of eager fans looking for any even minute changes there is no surprise anymore. On the one hand, there's nothing inherently wrong with players seeking information under every stone, especially in an age where forums are routinely clogged with toxicity and community managers have to don emotional armor to handle them. Players are information hungry after all, we want to know if we should stick it out with your game. A tidbit of information can determine whether we stay or move on to a competitor. Developers rarely brave those waters as it is.
On the other hand, the internet proliferates news faster than mono at a high school student's birthday party.1 Merely existing on social media can mean inadvertent exposure to spoilers of all kinds. Datamining can also open up the developer to feedback the mined content wasn't ready for.
Things aren't all bad, but it eliminates some of the mystery, and in cases like special events it removes any sense of an unveiling. It can also create problems for players that don’t want to know everything beforehand, as the community will expect that you know everything new going into each new patch. The knowledge can also be a problem for developers, who will suddenly find themselves on the receiving end of inquiries about changes that were experimental.
Much like how a DnD dungeon master might need to fudge rolls to improve the game, developers might occasionally need to "cheat" a little to make things work,2 and when a developer is relying on the digital dungeon master's screen of the game to hide some mechanics, it can get them some backlash when players are able to see around it. Just recently some enterprising dataminers figured out how to predict a "random" vendor inventory in Destiny. They even noticed that Bungie actually can tweak the vendor's inventory behind the scenes, and some are upset because they believed that Bungie was going to let the proverbial chips fall where they may.3
For good or for ill datamining is here to stay, but going forward I can't entirely blame developers for trying to hold back version updates and public test realms if it means exposing themselves to less knee-jerk feedback and to preserve a sense of surprise.
2 Though when we're talking about paid gaming experiences the amount of "cheating" we'll accept is significantly lower.