>>837090501-07 always had soul to some degree, it comes down to personal preference which is better/worse than the other. Robots stranded on a tropical island with subtle lovecraftian elements vs fantasy/sci-fi hybrid with more overt lovecraftian elements.
2008 started to pander to the Halofags and lost some soul (the Toa at least), but the Swamp was still a really cool setting.
By 2009, however, it couldn't even be counted as Bionicle anymore. But maybe that was a reflection of a problem that affected other Lego themes as well.
Mind you though, soulless doesn't necessarily equal bad. Most HF and G2 sets were actually pretty competently made, but by then Lego was well underway its transformation into a generic modern corp with a worldwide grip. So what we saw were decent sets stripped of all the concept art's soul. Goes the same for Lego's other original IP themes.