In almost all situations where behavior modification is applied to children (and maybe even in most clinical settings) it's because the adults want to control the child. My 2yo throws a fit when I tell him to stop playing and come eat so every time he does that I'm going to put him in time out for 2 minutes. Every time he comes to eat nicely (the way I like) and eats all of his lunch, I'll give him a cookie. That's about controlling the child rather than taking care of the child's needs. Maybe the child isn't hungry, in which case forcing or coercing him to eat would not be a good thing. Maybe the child isn't finished with his important work of playing. I know I would be furious if my husband took away my knitting and told me to either go sit at the table to eat or sit in the corner for 42 minutes. You'd be believe I'd be having a fit. Honestly, the more I talk about behavior modification, the more I think it is probably never appropriate.
I don't think you are being preachy but I do think we agree more than we disagree. Although, I do disagree with the idea that what Dad says goes no matter what. I think it really depends. If Dad says that everyone has to go to bed at 9 pm because he needs to go to bed then to get enough sleep before getting up the next morning but no one else is tired/sleepy, that's not fair. It's perfectly reasonable for Dad to ask everyone to be quiet or go in a different room if he's trying to sleep in the bedroom but it's not reasonable to insist that everyone turn off all the lights, get in bed and sit in the dark and be quiet because he's sleepy. There are many nights that I try to go to sleep early because everyone else is going to sleep but I just can't fall asleep. It feels horrible for me to force myself to stay in bed with my eyes shut willing myself to sleep not to mention that it's useless. I get up and do something else until I feel sleepy. It's no different for kids. If I wait until Kellen is ready to go to sleep, there aren't any problems. He says he's tired, climbs in bed, lays down and falls asleep even if the rest of us are still up talking and watching TV or whatever.