DWIM scalars: ie, the fact that numeric strings convert themselves to numbers in numeric context, and that numbers convert themselves into strings in string context. Overloading '+' for strings would break this behaviour; and I think pretty much everyone can agree that this is a Bad Thing. :-)

(Eg, what if you add a numeric string and a number together... Should they be concatenated, or added?)

bbfu
Seasons don't fear The Reaper.
Nor do the wind, the sun, and the rain.
We can be like they are.