Apparently a temporary unavailability ...I hope.
Yeah, I think I see your point. On one hand, we want classes to provide some unique/differentiated gameplay, and on the other hand, we don't know before hand what would be good choices and what not.
What I think is also important to keep in mind is that this is a story-oriented game, with very low emphasis on gaining skills and stats (No XP, levels, etc.)
...the different classes is more a way to enable different story paths or influence the way the player tackles various situations. (the rogue would steal and hide, the bard will negotiate and amuse, the wizard will use a magic trick or an illusion...)
There are also no constraints nor rules. You could be bitten by a vampire and become a vampire yourself, or become a necromancer. This would not alter the gameplay, since it's reading a story, but in the first case you may be able to fly but be burned in the sunlight, while in the other you could talk to a dead body. Since it's story oriented, there are almost no boundaries. The lifespan of the hero is also probably short. Once you read a few chapters, you finished the adventure!