Another good point, but if bar A is twice as tall as bar B then variable A's value had better be twice that of B's. Anything else is precisely the kind of shady drug-company data manipulation that you're so concerned about. If vertical space is at an absolute premium (not the case here IMO) and you have to cut the bars then draw little cut marks on them to let the reader know that the bottoms aren't at zero.
(Of course I'm talking about cases when there is a familar concept of zero, like percentages or money or population, not temperature. And if the value goes negative then the bar grows down, cf. any recent chart of US economic indicators.)
If you don't base your bars at zero then your bar chart exaggerates differences between data because the reader looks at two bars and compares their relative sizes the same way he looks at the levels in two glasses of beer to compare their volumes.