But you could easily have problems filling a table that way. If you say, prepare a scifi campaign, and it turns out your players aren't interested in playing a scifi campaign at all, then you're done. It is not exactly the best approach, unless you happens to have a group who is okay with anything you run.
If instead you first ask your players if they would be interested, and give them a rough outline of what they can expect, you would be far more likely to get everyone on board. You would be far more likely to avoid that type of conflict, like someone insisting on playing an elf, and you'd save yourself a lot of work in the case that they are not interested.