Well bees are definitely objectified and seen as industrialized honey producing machines. They're starved of their own resources and are given mostly sugar water in return. Bee keepers are not concerned with their well-being other than for production yields. It is a form of factory farming. Isn't this reason enough?

They're certainly exposed to a very different living situation than would be typical for them in most cases, to their detriment. For example, bees that make their combs in frames lose substantial heat from their hives, which usually helps protect against disease and even predation. They're also often given a sugar water substitute to eat when their honey is drained off for human consumption, which is nowhere near as nutritious. They're also moved around on the bee keeper's schedule, which may be a substantial stressor compared with a hive that stays in one place. Never mind that they may be exposed to climates that substantially differ from where that particular variety of honey be evolved.

Given issues like colony collapse disorder, it's pretty clear that many forms of bee keeping aren't really great for bees. Does that constitute torture? That's hard to tell, but it certainly does put pressures on them in multiple aspects of their lives and the lives of their hives as a whole that they wouldn't be dealing with otherwise, and which probably aren't pleasant.

Would you consider it torture, or at least cruel, to forcibly relocate the population of a city to an area that's freezing cold, force them to live in poorly insulated homes, make them eat food that isn't healthy for them, and steal the product of their labor in exchange for their efforts?