Avionic LRUs having increased temperature tolerances and other desirable properties are provided, as are aircraft systems containing such high temperature avionic LRUs. In one embodiment, the avionic LRU includes at least one microelectronic device and an LRU housing, which contains an enclosed cavity in which the microelectronic device is located. The LRU housing further includes an electrically-routed housing wall having an inner principal surface or frontside, which partially bounds the enclosed cavity and to which the microelectronic device is bonded or attached. The avionic LRU further includes a first LRU connector interface having a first LRU terminal array. The first LRU terminal array projects from the LRU housing and is electrically coupled to the microelectronic device through the electrically-routed housing wall. The LRU connector interface is configured to matingly engage the receptacle connector interface to support LRU operation when the LRU is removably mounted to the avionic LRU receptacle.