I tend to agree with this. It's partly why I'm on the fence about him. He's not really given much to do until later in S1 and in S2.

Also, it does appear that power or the lust for it - brings out the cruelty in him? Because in Long Ago Far Away - when he decides to not free her - is mainly because of the prison of power, which he wants to reject. And note in the episode where Clone!Rebel!Dawn confronts Real!Rebel!Dawn - Clone!Rebel is cruel partly because he has power or wants to take it away from Real!Rebel!Dawn.
I honestly think the weight of Empire is what makes them cruel.

What I like about this series - is the writers deftly show that they are capable of gracious and even kind acts in the midst of the cruelty. Showing how people are more than one thing - and not just one-dimensional or stock villains. I mean, all three of the Clones are capable of cruelty and kindness.
As is Hari Seldon. And Lady Demerezel. I think they tend to fall toward cruelty when power is at issue, or the temptation to abuse it.

Also, I'd say, you are correct - the Dawn's do show more vulnerability and attachment as we move forward in the series. I did find how each version handled Demerzel interesting - Dawn leaves her trapped, because he is trapped, Day puts her back together and clothes her, but doesn't free her.
Dusk frees her from one cage only to put her in another one, making me think that he waited to free her until he could figure out how to make her his personal cell mate. I'd say prisoner, but I honestly think he felt he was in a prison and desired a companion who would co-exist in it with him for eternity (of sorts).