kEiThZ
Superstar
It's fairly invisible - to the average Joe both armouries are a bit of a mystery. Granted, there are issues around security - but it would be beneficial to have more of a public face to both facilities I think (housing perhaps relatively insensitive uses like regimental libraries/archives, etc.)
AoD
Part of it is security. Would you want random strangers walking through your office any time? Particularly if there are security concerns?
And part of it is history. Many of the regiments in Toronto have a long history in the area. So they tend to have other facilities around town. For example, Casa Loma is the regimental museum of the Queen's Own, I believe. And St. Andrew's Church has the 48th Highlanders museum. The armouries themselves are largely working facilities today. The few historic artefacts that may be in these buildings are largely private to the unit itself.
They do have a mandate for public relations though. More so, than the regular force. So they will tend to host family days, community days, etc. In years past, reservists tended to be active in Toronto events, like the Dragon Boat race. Not sure now.