Do you believe that Luke 21:1-4 is an example to follow, or a means of convincing someone to tithe?
I mean, looking at the surrounding context, it's just an odd transition: "hey watch out for these scribes, but get your tithe in and by the way I am going to let this temple be destroyed." But if you read it from how I read it after doing some work in translations it came across more like, "hey watch out for these scribes; they want popularity and attention and they take advantage of widows, like look at this widow here giving out of her poverty all she has to live on for this temples building, which by the way I am going to destroy."
You are right: it is an interesting juxtaposition! The very thing she gives to is going to prove temporary (to be destroyed in two short generations). And yet she gives.
I never thought the passage was to get us to tithe. Her spirit is commendable, and demonstrates giving with faith, which is applicable to a wide range of situations.