>>>What's so great about sliced bread?
>>What is not so great about sliced bread?
>
>It's nothing special. Anyone who isn't exactly all thumbs can slice bread. I don't see anything epochal in it, to merit the saying "...best thing since sliced bread". So, this is linguistic archaeology, i.e. trying to dig out why do we say so.

Perhaps, "This is the best thing to come along since the invention of sliced bread." is a better way to say it.