absolute or relative improvement with IS?

I consider the 18-55mm kit zoom a mediocre (i.e. average or ordinary) lens, but it has given me some great images which would ordinarily have been lost, thanks to its IS. I consider it a tragic mistake that Sony, which owns the patents to Minolta's IBIS, chose to omit IBIS from the NEX line. With IBIS, we would have IS with every lens, including the superb Sigma lenses, the Zeiss 24mm, as well as all the great adaptable legacy lenses. Instead, Sony forces us to buy IS in every lens, thereby driving up the size and price of every lens with IS. Come on Sony--Canon uses IS because they don't have IBIS! Why imitate them?

Sony needs to break free from their mistaken idea that the NEX is a glorified P&S. Mirrorless is the future, and should be given every advantage formerly bestowed on DLSR, including IBIS.