Does this significantly negatively impact the lives of viewers or of those around them? Addiction doesn't just mean "want to have it". Addiction means "want to have it so bad it messes up other aspects of my life".
(For what it's worth, I do personally avoid cliff-hanger shows because I find the anxiety and frustration of being left hanging is rarely sufficiently well compensated by the quality of the show.)
It's also a good trick for going to bed on time and breaking the 'just one more episode...' problem!