Alright, so just to consolidate all the replies, the reasoning behind the titanium being there is because most folding knives still use a liner lock and carbon fiber isn't well suited to be used as a liner lock.
I do not own any titanium construction knives as of yet (my collection is kept under a dozen knives) but I do own a 940-1, which is full carbon fiber handle scales. I know that Benchmade's axis lock and Spyderco's back lock allow it to circumvent the need for a liner lock but I think full carbon fiber can still be done on a liner lock if someone were to put in steel/aluminum inlays and extend that into being the liner lock. It won't be identical on both sides with the steel liner jutting out from underneath on one side but it could maximize the carbon fiber into a more uniform look.
Here is a WE Eschaton liner lock folder. The rear end of the frame is Titanium in one piece, The front end of the frame is C/F in two pieces. The lock (leaf) spring is steel. The spring is bolted in 2 places to both the Ti and the C/F. In the 1st picture, you can see the 3 layers fastened together. The C/F is on the left, the Ti is in the middle, and the steel spring is on the right.
