I think the supply bottle-neck is the reason. All the pot has to come from a few hand-picked suppliers. Also there are claimed Liberal ties to pot production. Some quick links (although I suggest taking this with a grain of salt given the source):

https://potfacts.ca/the-liberal-party-elite-is-heavily-inves...

https://ottawasun.com/2015/10/28/liberal-cfo-could-rake-in-m...

I haven't heard any moral outrage arguments in the press or otherwise. Remember that this isn't only a youth issue or it wouldn't be used in a federal campaign promise. It is, by definition, widely supported. Recall that people well into their 60s and 70s came of age smoking pot.

IMHO there's much more moral outrage associated with the Conservative plan to reduce drinking restrictions. Ontario remains a pretty uptight place.