"Ti is not a suitable material for trekking poles because it's prone to cracking under bending stress."
I know nothing about the metallurgy of Ti, but could this be a function of the Ti alloy used?
That some Ti, for instance that used for golf clubs, IS prone to cracking while other Ti may do well? What ever is used in bike frames seems to do OK, and the seat tube is in a similar compression mode. Offhand, I can't think of any other applications that are close to "trekking pole mode".
As to price, this does seem to be a pretty "price insensitive" crowd. Even though Cuben is hard to justify on a $$/lb basis, it sees a lot of use.