It probably hasn't been brought up because no one can change it -- if the dollar continues to slide, imported goods will either keep rising in price or offer less value (i.e. sizes are going to start shrinking). I don't think anyone wants to campaign on reducing grocery bills when they know it wouldn't happen.
Well I would agree, but there's a problem with that argument. Our dollar wasn't particularly strong back in the Chretien/Martin days, but the price of groceries was lower than it was when the dollar was strong under Harper.
The price of groceries is just ridiculous now.