If I recall correctly we predominantly use Personnel Support personnel to do Infrastructure? Not surprising then, surely civil engineers would be a better choice?
I was a pilot while I was serving and have never worked in DIO, or DE, or anything else infra-related, but I am reliably informed DIO uses lots of civil engineers, including those of the RE! The issue has always been lack of investment, or rather a budget that was not big enough to do everything that was required. From the HQ level, the infra budget was an easy target, so it was inevitably reduced - the station I was on was given 10% of the 'operationally essential' works budget one year. That meant prioritising in the certain knowledge that deferred work was only going to get more expensive. When faced with a choice between doing preventive maintenance on a flat roof or sorting out the erratic power supply to the runway lights, it isn't actually a choice at all.
The system has never been perfect (and often far from it) but it remains to be seen whether managing spending priorities from HQ AIR will have the impact that people seem to be looking for.