I really don't have an answer as to why Torre keeps alternating bottom of the order spots with Kemp, but with that in mind, it wasn't a surprise to begin with that Torre would keep juggling the order (more so since Manny has been out).
That said, Kemp has continued to improve and produce. He's working counts better and he continues to walk more. Why he isn't moved up the order, who knows, perhaps it's a reputation thing for once being a hacker or as a baserunner who had made poor decisions (think there was such a moment in last Friday's game if I recall correctly). At any rate, I do believe management and Torre still rate Kemp very highly, but I think they view Kemp as a work in progress, who needs steady development, I reckon. Like h0rt said, Kemp is still producing no matter the spot he's in and I think with the Dodgers have a nice cushion in first, Torre probably feels he has time to tinker his lineup some. My guess is as good as yours really.