Not to defend incompetence, but could the design have made it a bit unwieldy with the 900 (US) ton receiver housing the array of focusing lenses/mirrors? Is it common enough to suspend something that massive from so few points?
The only comparison I know is the FAST which opted to actively deform the dish itself for focusing rather than suspend such a heavy receiver.
The original platform didn't include the Gregorian dome. The auxiliary cables were added in the mid 90s during a major upgrade that included the dome, adding a considerable amount of weight.
The choices were made based on funding and ability. The main platform, towers, and reflector was designed and constructed in 1960, long before our computing capabilities could have even conceived of being able to accurately deform the surface. Heck, the reason the dome is so massive is that it holds a secondary and tertiary reflector to convert the focal line (an artifact of the primary reflector being a spheroid instead of a parabola) into a focal point.
Also, the 30-ton platform in FAST is the main limitation preventing FAST from being able to perform planetary radar science. It is too small and cannot support the weight necessary for a radar system of sufficient capacity.
In lots of telescope designs, the sensor is behind the dish. The part in front of the dish is only a reflector. Done that way, weight of a transmitter doesn't matter.
The only comparison I know is the FAST which opted to actively deform the dish itself for focusing rather than suspend such a heavy receiver.