However, the question becomes murkier when we talk about what some might consider a kind of internal compromise. When is a change in position an evolution of ideas, and at what point is it a compromise? Take, for example, Robespierre's views on the monarchy. When he became a republican, was he compromising with the current political climate and possibilities? Or, on the other hand, was he compromising before when he supported a constitutional monarchy? Or both? Or did his thoughts on the matter merely change with more reflection? Or was it a combination of all three? However you slice, it there is almost certainly some kind of compromise involved.

To look at it from yet another perspective, there are probably those who say "Robespierre was incapable of compromise" and mean "Robespierre was self-absorbed and didn't care about the opinions of others." Which I don't think is true. You can't expect anyone with principles to do anything but combat the ideas of those whose principles are diametrically opposed. I mean, what do people want Robespierre to have done, said (to continue by example from above) to the colonial lobby, "you know, you have a point about the British potentially getting control of our colonies if we abolish slavery"? It doesn't make a whole lot of sense to me. And situations where it is likely that he listened attentively to someone else's views and adopted him are likely to be invisible. Take Lepeletier's education bill, for example. We only ever see him proposing it to the Convention after Lepeletier's assassination, on the latter's behalf. We don't know what his views on education were before he read it. Quite possibly they were different but Lepeletier managed to convince him. We shouldn't assume that everything Robespierre ended up supporting was something he supported from the beginning, and still less that he came up with all his ideas in isolation from his colleagues.

I think as most people do make compromises, and perhaps feel guilty about them
If people are making the kind of compromises they feel guilty about, they need to realize that that's their own issue and deal with it accordingly instead of taking out on historical figures. Beating up on Robespierre because you can't beat up on your conscience speaks much better of him than it does of you. I think I saw a biography of Robespierre once that called him "the conscience of the Revolution." It's very apt here.

Robespierre is a rather tempting target to attack if one wishes to defend oneself against the charge of being an out-of-touch theorist who has no concept about what goes on in the real world.
Very true. Though I always wonder what individual academics feel targeted by this as individuals when I've always seen it as a generalized attack the concept of academia. You would think they would know better than to buy into those kinds of stereotypes to the extent that they feel it's necessary to put up the kind of defense that says, "Yes, academia is like that, and this historical figure I'm studying was like that, but I'm the exception. See how relevant I can make myself, see how I can jump through all your hoops and fit myself into the mold you're really trying to prescribe for me. Not like them." Bizarre, really.

And look, my post(s) is/are long anyway! XD;