I'm a designer, not a marketer, and not a writer (at least not professionally). A lot of the work I do involves working with material in a field that can be above my head. Because of that, I'm content to take the text that's given to me and do what I can to make it look great on the page – tighten the kerning to get an orphan on the previous line, adjust size and leading to get it all on the page, play with gutter widths, and so on.
But sometimes, it's tough to avoid the rivers or repetitive words or even orphans sometimes without altering the copy itself. When it's my work I have no trouble doing this, but when it's someone else's work (particularly when they know more than I do and might care less about such issues as I do), it's harder to make a case to change wording simply because it doesn't look ideal when on the page.
Is it a designer's place to try to alter wording on the mere basis that it doesn't look quite right on the page? With apologies to David Carson fans, I believe that form follows function, not the other way around, so the answer would seem to be no. But tweaking just a few things can often make a big difference!
As sort of a side question, would altering text thus be a last resort? I do not like to hyphenate anything, but would it be better to do so than alter copy?