Personally, I think this has been a long time coming...
I collected 6 of the 7 original Toa, got all the Bohrok, and a couple other sets here and there, and, while I was subscribed to Lego Club, followed the Bionicle comic books that came with the magazine each month. But then I realized that the whole Bionicle line goes basically nowhere... Let me explain;
Step 1: New heroes introduced (Toa, Toa Nuva, Blabbingtons, etc.)
Step 2: Villains to counter said heroes are introduced (Rahii, Bohrok, Rakshii, Poopyheads, etc.)
Step 3: New "boss" character introduced to tip the scales in favor of one side or another (Makuta, Takanuva, John-Bobby, etc.)
Step 4(a)[optional]: Previous heroes are recycled by receiving upgrades of some sort
Step 4(b): Previous heroes die/vanish into obscurity to make way for new heroes
Step 5: Repeat process, beginning at step 1.
Think about it... There are maybe a few notable exceptions to this rule, but otherwise, that sums up the strategy pretty well, yes?
So once I figured this out, I decided to pretty much turn a blind eye to the whole thing. To this day I have no idea what the heck happened to the orginal Toa, except that pretty much the only way to find out about it was by reading some random book...
But despite my personal pleasure at this news, I'm surprised that they're completely doing away with such a major cash cow just to basically experiment with a replacement...