Please look at
Show[DiscretizeGraphics[Graphics3D[{Cone[]}]], Axes -> True, Boxed -> True] 
Well, there are some Ticks, but others are missing or (on the Z-axis) cut-off.
Now it becomes even worse:
dg = DiscretizeGraphics[Normal @ Plot3D[Sin[x + y^2], {x, -3, 3}, {y, -2, 2}]] // Quiet Show[dg, Axes -> True, Boxed -> True] 
The Ticks are completely missing.
Is this a bug or do I overlook something?
EDIT
Thanks to hieron's answer:
Show[dg, Axes -> True, Boxed -> True, SphericalRegion -> True, PlotRange -> {{-3.2, 3.2}, {-2.4, 2.4}, {-2., 2.}}] 
However, we don't need this work-around with
Plot3D[Sin[x + y^2], {x, -3, 3}, {y, -2, 2}] 
Show. $\endgroup$Quitwithdg = Cases[Normal @ Plot3D[Sin[x + y^2], {x, -3, 3}, {y, -2, 2}], GraphicsGroup[__], ∞][[1]] // DiscretizeGraphics$\endgroup$