Alpha blotting again

I’m just wondering what is the reason that SDL just keep the destination alpha when blitting RGBA surfaces instead of using something like (1 - ((1 - srcA)*(1 - dstA)))? Is there any chance that this behaviour is going to be changed in near future? In its current state it is impossible to create a surface as a composition of some existing surfaces having transparency (for example to put several surfaces from TTF_RenderUTF8_Blended() together).

Thanks in advance,