Well, as much as I didn't like the F2 choices this year, doing what you said would make the show very dull. It would be much like season one. As some may recall, season one enabled the viewers to vote on an eviction, and since the contestants knew this, they would commonly "hold back" in the diary room, so as not to upset or offend the viewers. In seasons two through seven, the house nominated and evicted all houseguests, so they only had to answer to each other, with the exception of America's choice, which did not directly affect the outcome of the game, though indirectly put the FS in their place. As much as I would have spent all night voting for Kaysar or Janie if I could, that would have undermined the entire concept of the show, which is a game, as much as some of us (including myself) hate to admit. I believe CBS has the power to manipulate the game to a point, and they very well could have had Janelle win HOH and make the final two, but they choose the methods they choose, and there's nothing we can do about it. Everyone will complain for a few weeks, nothing will really be done, and we'll all come back and watch again next year.
P.S. In case you're wondering, the application for BB7 is up, so I think it's safe to say there will be a next year...Please, CBS, no more twists, just a bunch of diehard gameplayers is all we need.