Everybody likes “the new hotness.” Everyone loves a new car, or a new computer, or the state-of-the-art video gaming console. It’s why people camp out for days to get their hands on a new iPhone, when they could just buy one the next week off the shelf. People love to have the hot thing, right now.
Perhaps, then, it shouldn’t be so surprising that people get tremendously excited when a new version of PHP comes out. People look forward to the new features, whether they be the trailing commas in list() syntax or counting of non-countable objects.