Heh! I agree with you on that. When the "one-clicks" work they are slightly more convenient than doing it yourself, but not that much.
I've had good result with the ones I have tried, which is most of them, but I've never done the PhpGedView. Frankly, I would almost always rather do my own "upgrades" anyway - I just trust the "manual" process more, especially if any customization was involved (and it often is!).
To me, their biggest value is to those who can't do their own installs - for them it might be the only way to be able to use some of these applications.