Staying around longer--what those additives have in common. . .
is making stuff last longer so it is good out on the shelf to SELL.
Fresh cake flour, good butter, careful mixing and attention while baking are what make a home-baked cake better than store-bought. And MY homemade cakes last just fine with plastic wrap to cover or in a covered cake carrier.
I mean, how long should a cake last? If it is around too long, it is either not the best you have done OR too much. If it is not your best, dispose of (or work into another recipe somehow) and try again. If it is too much, freeze half of the thing and enjoy later!