As Migeru notes, pH 7 is somewhat arbitrary.

But of course it's not entirely arbitrary -- a condition with equal concentrations of H+ and OH-, with their sum at a minimum, is a special point.

But "7" only approximates this point, and many chemistry texts lie about that.

But also, many processes are sensitive not to the balance of the two, but to the concentration of one, and each varies smoothly with no discontinuity or change of sign at pH 7, which is why pH is defined in terms only of the concentration of H+.

But "more acidic" implies that the state is already in the "acid" range, which it certainly isn't.

But "acid" is, just discussed, physically arbitrary.

But it's standard usage.

But even the term "acidification" would seem to mean making acid, which isn't a prospect.

But "dealkalinification" would do the job.

But that would be pedantic, and the discussion, once it's out of the journals, is aimed at public understanding, and above or below pH 7 is beside the point.

But what about Lewis acids -- should Brønsted acidity get all the attention?

But "but" is a fun conjunction to abuse.

But "in conjunction with" means roughly the same as "and".
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There is a need to fill slots in sentences like "Because there is more CO2, the oceans are becoming more ___", and this encourages the use of "more acidic", despite its faults.

If the issue gets into popular culture, you know that he cartoons will show the oceans burning people, dissolving boats, and so on. The oceans will be about to become "acid".

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