dynamic marks vertical alignment

[luis jure]

hello list, apologies in advance if this is silly or obvious, but i've
been away from lilypond for some time.

i realized that by default lilypond puts dynamic marks aligned at the
top, resulting in poor alignment of pianos and fortes. for example, this
code:

\relative c'{ d'2\fp d2\sfp d2\f d\pp d\f d\p d\mf d\mp }

produce the attached image (tested with both 2.12.2 and 2.13.3). 

is there a rationale for this, or is it a bug? i think dynamic marks
should be aligned at the baseline, like all text. (by the way, compound
marks using both f and p, like fp and sfp, are correctly aligned, as
you can see in the attached example).

best,

lj

matices.png
Description: PNG image