As much as we all hate them, there are a few reasons why glass ampules still exist. The primary reason is that some medications just cannot be stored in any type of plastic. NTG for instance is absorbed by plastic over time. It's not a significant amount when running through plastic IV tubing, but if it was stored in a plastic bottle or bag then the actual concentration would vary significantly by the amount of time it had been in contact with plastic until there was essentially no active medication left in the solution. Even worse, some medications not only become less effective when in contact with plastic, but they can actually become potentially harmful. Some medications react with some plastics but not others, such as Aviva plastic.
Another argument for glass is that rubber stopper vials are universally seen as multi-dose, even though some medications stored in them become inactive even after a small amount of oxidation, glass ampules have the advantage of being single dose by their design.
There are even arguments that more medications should be stored in glass vials for other reasons; I heard of a nurse who emptied out all the morphine and dilaudid PCA syringes through the rubber stoppers and refilled them with NS, which can also be done with carpujects and vials, but not with ampules.
I absolutely agree that for storage reasons, we still need to use glass, although I don't know that I would advocate putting all narcotics in sealed glass just for security or as a replacement for education on multi-dose vs single dose vials, but they are both arguments out there for the continued use of glass.