I feel for the crew - as has already been said "there but for the grace of God".
One can imagine certain factors such as poor signage, lighting and/or charts.
Maybe "someone" head down reprogramming FMC for change in SID/departure?
Am enjoying my retirement doing some light aircraft these days after an airline career - I find myself constantly nagging people to slow down on the taxi speed!
I know airlines have max speeds which are monitored on OFDM etc but the key point is slower taxying speeds give you more thinking time and if any doubt then STOP.
Am sure the report on this one will be very interesting - holes in the swiss cheese methinks.