I wouldn't say that things have been half-a$$ed, at least not by the STM.
As far as accessibility is concerned, the STM has more of a tendency of over-engineering rather than half-a$$ing things.
At Bonaventure, the STM installed elevators to the mezzanine in 2008-2009, expecting the AMT would be able to build the rest of the elevators to the bus terminal and street level simultaneously.
For their 3 elevators (metro mezzanine -> terminal, terminal -> street level, street level -> terminal north), the AMT needed to sign a lease with the building above the station (1000 de la Gauchetière), which houses both the bus terminal and the accesses to the metro station.
Because of the complex structural work involved, the negotiations ended up dragging for many years. So much that the plans for the elevators they were planning to install had become outdated in the meantime! Which meant plans being redrawn, and more negotiations!
Work for the elevators finally began in January 2017 and the station will become accessible in early 2019, a full decade after the STM installed its elevators!
Ironically, the AMT (now exo) bus terminal will become pretty much deserted in 2021 when the REM replaces the south shore buses.
The cours mont-royal handicap door is just the mall owner doing its own thing. It's not part of any plan to make the Peel station more accessible.
The STM is prioritizing McGill (2020), Berri-UQAM (2020) and Place-des-Arts (2021) as the first accessible downtown stations on the green line.