I can take some stabs in the dark about motivation.
Ford: I think this is all about control. Every episode so far has brought up the Board that oversees Westworld and it’s pretty clear he does not have a good relationship with them (I suspect they are of the fat-lazy-cat variety and care more for profit than they do for whatever Ford’s original intentions were in creating the park, like tackling and unlocking human consciousness). He obviously has a huge ego–one that sees himself as a God in his own world, a God that is now being trodden upon by said Board. His new storyline and what he’s building will establish him as the sole ruler of Westworld, the Board be damned.
The Man in Black: I actually think he’s the most honest of all the characters. It’s a nihilistic type of honesty, but it’s honesty. He’s bored. He’s read the same book day after day for 30 years; he k knows every sub plot, every twist and turn, except the ultimate last. It’s like…okay, have you ever a classic mystery novel? Think Agatha Christie. The reveal of the murderer and their entire explanation happens in one swell swoop typically at the very very end. What if you had a book like that but the last page, the one that revealed the murderer and why he did everything he did, was missing? Wouldn’t it drive you somewhat nuts? (There’s a great episode of MASH that actually follows this exact plotline come to think about it.) The MiB doesn’t even try to hide what he’s after or how different he is from the rest of the world. He straight up tells Hector that he, Hector, is “market tested” and that’s why Hector exists. The MiB also goes around telling people that they are prisoners and he’s trying to find freedom. I don’t think he cares about them, but is so bored and nihilistic that he’s looking for the only escape left and if it means the Hosts get freed then so be it. (sidenote but what does freedom actually mean here? The more I think about it, the more I think that the Maze and freedom aren’t literal but figurative. The Maze is more about unlocking human consciousness and freedom is less about leaving the Park–we know the guests can leave after all–and more about freedom from something less tangible)