The problem is, Turkey had been warning the Russians for months that if they keep doing it they will be shot down...we all know what happens if you make a threat and don't go through with it, i am not saying it was the right thing to do but we can see why it was done "to prove we can and will"
You cant just keep busting a nations airspace with bombers 1 mile or 100 its the same, because if nothing is done 1 miles after time becomes 5 miles then 10 and so on..Russia had been warned many many times about this