That's an over simplification.
People could still have more free time than we do now[1], while their life could be more monotonous on some aspect, I believe an average office worker life today can be even more monotonous than what a serf life could be. You also have to consider labor alienation, which is a something that didn't exist so much before industrialization.
Most importantly, life commonly revolved around tight communities, while today most people live in individualist societies.
Individualism certainly has a larger impact on happiness than most modern convenience has.
- [1]: https://groups.csail.mit.edu/mac/users/rauch/worktime/hours_...
No, preindustrial ages weren't the hell they're made to be nor a golden age by any means. The same can be said of today. Stop playing defensive and think openly instead, there's lot we can improve by learning from the past.