Every Citation flying has AoA displayed, both as a guage and a reference on the ADI or PFD depending on age. Similarly the L1011 has it, and upon selection of landing flap the speed selector on the MCP is hashed out and the AP/FD targets AoA whether you like it or not (If I am recalling correctly - it was 25 years ago!). And as has been pointed out Concorde had it.
Therefore all this discussion of why it can't be done is some 35 years behind the times - it can be done, but as usual cost comes before mere usefulness until there is an accident.
