Your view on Buick is seriously misinformed. You didn't even give an honestly legitimate reason for this decision other than your statement that said "Buick has become the red-headed stepchild at GM," which it really is not. What is wrong with the car specifically? Are there any serious mechanical issues? Serious quality issues? If your individual example of the Lucerne had a glaring, major fault I would understand all of this, I suppose.
Just because Buick does not offer 15 models does that mean they are "GM's red-headed stepchild" and it warrants your trading in of your Lucerne as a means of hopeless protest, which is what this all sounds like.
Well, in the end it is your decision and I will choose to respect that, although I do question it.