This is, in fact, one of the central themes in the books. Many wizards, like Umbridge, see nonhumans as subhuman. They don't really believe them to be fully sentient, or belonging on the same level as humans. At best, they are things which need human protection to keep them from hurting themselves.
Contrast this with someone like Hermione who fought for (what she believed was) the well-being of house-elves. Contrast this with other Wizards who treated non-human sentients as equals. In many cases, the way a Wizard treated non-humans was used to demonstrate their character.
As far as Harry goes, I see him using the methods he did at Gringott's only as a last resort. Destroying that horcrux and vanquishing Voldemort topped off everything else. He couldn't allow anything to stop him. I'm sure using the Imperius Curse and releasing the dragon were the last things he wanted to do. He knew innocent people might be hurt. Then again, if he failed, all those people would end up dead anyway.
Certainly that's how he saw them, but I still see it as reflecting poorly on his character.
Further, I would have liked for him to have been a little more straightforward in telling the goblin his intentions--to wit: to destroy certain dark magic artifacts, one of which was likely in Bellatrix's vault. He did not want to remove anything from the vault--merely destroy something that was there--but he needed Godric Griffindor's sword to do so.
Given the difference between Goblins' and humans' perceptions of ownership, I would think presenting things in that way might have caused him to be seen as less of a thief.