Yes, it certainly can be terrorism if it's done with the eventual goal of effecting political change by forcing governments to pay attention and that kind of thing. Certainly as written in Canadian law, then, property destruction can be terrorism.
The difference is that terrorism is a rainbow. There are all sorts of things that are called terrorism. If you want to prevent people from being injured or killed by terrorism, then you have to ask, if you have all of those things included in the bundle of terrorism, if that is actually the most efficacious way of stopping the things you're most concerned about.
I'm not in any way saying that we shouldn't care about property destruction or that it shouldn't be the subject of law enforcement, but the way terrorism is discussed and policed means that you might be sacrificing more effective prevention of human injury by pursuing property destruction under the terrorism framework.