If a politician changes his view and publicly states that he held a very different view before but he was swayed by x, y, and z then I think nobody would accuse them of flip-flopping.
For example, John Kerry's "for it before I was against it" sounded to some like he was dissembling and hiding that he may have changed his opinion on an appropriations bill simply because the wars were becoming less popular with the public.
You can honestly change your opinion and point of view, and you can also lie. Changing your opinion and point of view is not seen as negative, but deception is generally frowned upon to the point of societies making fraud a higher level crime (see Perjury).
So, the verb form is OK but the noun form is absolutely not.
Or perhaps another way of looking at it is they are trying to represent voters better. Since that's, well, their job.
We should not get onto politicians for representing voters, rather than themselves. Changing their approach to public policy is a very good way for a public official to better represent voters.