I don't think people are upset because they are assuming the classical album means no more new songs, but because there were expectations for more new songs when she posted about Winter diary, and these were let down by a classical album, me included
Some people find would prefer trance/house/eurobeat remixes, and some don't care for classical mixes, or remixes at all, it's not such a big deal to understand this is a release that do please not many fans of hers
I myself think I would be much more excited about this if we got the classical announcement and after it the announcement of a new song in it, so there wouldn't be expectations for new songs and everyone would be surprised. The problem is not the classical album itself, but the expectation made around Winter diary (the song)