There hasn't been a class of drugs I haven't abused extensively and judging by this extensive personal experience on one hand and most recently published literature on the other, I am most positive that caffeine fulfills all requirements for causing both physical dependance and mental addiction.

There will actually be a looong list of caffeine abuse related diagnoses in DSM-V, I was quite surprised myself.

The fact that moderate coffee consumption has a lot of positive effects on physical health (and alertness lol) and that it can potentially aid a society to function more efficiently (e.g. decreasing rate of traffic accidents) doesn't cancel out the fact that it is causing addiction and dependence.

Now I'm not saying "No!" to coffee personally and I don't think that there should be any severe restrictions, but be aware that caffeine dependence is a very real (and imho underestimated) phenomenom and that you might not want to expose those who have not yet reached full physical developement. Restrictions for the underaged as there are for alcohol and some public debate would probably lead to a more responsible attitude towards the substance.

On a sidenote, it has most definitely aided in facilitating my first full-blown manic episode and several psychiatrists have specifically asked me if there was any abuse of caffeine aside from other stimulants... There are a large number of genuine articles out there, just search pubmed for caffeine and mania or psychosis.