From the photos this looks like it might be an isophase bus GSU transformer, which is responsible for stepping up generation voltages for one or more generation units to substation voltages. These transformers are large, very expensive, very long-lead custom designs and consequently are closely monitored for temperature rise, hydrocarbon gas discharge, and gas pressure, in addition to various other electrical relay protection schemes acting on the faster electrical damage hazards. They are usually very well protected against all possible major equipment failures. The fact that this happened is an enormous screwup, it's not even within a few orders of magnitude of the power pole transformer that blows up during a lightning storm or similar.
Yes, but more like 20 years than 2. A lot of utilities out there are failing to properly maintain major infrastructure due to a a lot of complex factors not the least of which is that maintaining things is fundamentally 'unsexy' to management