I, too, am curious about the negative effects of coffee (or caffeine, rather). The potential positives are well known through many studies like the OP, but it is also well known that caffeine triggers a stress response (increased adrenaline, cortisol). We know that stress, beyond a short burst, is detrimental to health.
There seems to be a wide variety in different people's caffeine sensitivity, but for me, a coffee habit leads to a downwards spiral that ends with permanent tension and migraine episodes. I have tried this cycle enough times by now to know the cause and effect. I have to wonder what other effects the continued stimulation of caffeine has.
Sensitivity varies wildly for for different people. I seem to have a very low sensitivity - the only time I have felt the effects was on a barista course where I think I was up to 6-7 double espresso shots in the 90 minutes.
I drink espresso in the morning, black coffee through out the day and stop before dinner. It's around 4-8 mugs every day. On holidays I often go a days without any coffee for various reasons with no ill effects. I have gone an entire month substituting coffee with water to test the hypothesis that it doesn't really affect me and I felt no different. HR, BP, sleep quality, tiredness, mental performance, digestion all remained stable.
My neighbour gets a headache if he skips coffee for a day.
There seems to be a wide variety in different people's caffeine sensitivity, but for me, a coffee habit leads to a downwards spiral that ends with permanent tension and migraine episodes. I have tried this cycle enough times by now to know the cause and effect. I have to wonder what other effects the continued stimulation of caffeine has.