Well you're probably right about the Pico $$$$'s for Craig maybe.
Personally wouldn't class the trees as over mature, nowhere near that, but certainly under severe pressure form all that has and has not been done to their root systems.
What I find most frustrating about instances like this is yes it will be played out in the press as unsafe trees being removed and remaining trees being made safe....rubbish no tree is "safe" there is risk in all trees, in all things in fact. We all accept huge levels of risk in our lives every single day but as a community seem to have tree phobia or at least big tree phobia.
There are lots of options for the management of these trees and even trees in a worse state than these jacarandas. There are enormous values associated with bigger older trees, but this seldom if ever gets discussed or calculated...just a tree, or 2, or 3 cut them down, plant some others (only they rarely ever do)
It is possible to quantify the risk in these and all the trees owned by BCC, it could then be possible for the council to decide on what level of risk they will accept and how they will manage the assessed risk in specific trees..it does not have to envolve the removal of trees or parts of trees...it might...but it doesn't have to.
The values that big trees have should be part of what the council is projecting out into the community, how much carbon, how much airborne pollution, how much UV interception, temperature modification, rainfall interception etc...... then maybe more people would put more value on their own trees, and make better informed decisions about weighing real risk against real value.