Our Universe appears to be expanding and cooling, having originated some 13.8 billion years ago in a hot Big Bang. However, it's plausible that what we see from inside our Universe is simply the result of being inside a black hole that formed from some parent Universe. If the black holes that form in our cosmos give birth to baby Universes, perhaps we arose from the formation of a black hole ourselves.
It seems like you are making the assumption that time and the laws of physics follow the same rules inside the singularity. If we ourselves are inside a singularity, the net result was enough matter to create our known universe... but maybe in the next layer down matter behaves differently and stars can be produced on a smaller scale. Or maybe the matter is heading towards its own scale of big-bang. And what if time contracts to the point that the life of the black hole, and its relative size, corresponds to the life of that universe and its expansion?
A story which comes to mind and presents an interesting theory that could apply here can be found in He Who Shrank.
But you're still judging all of this based on our current laws of physics, or that anyone even knows for certain what is occurring within a black hole. Also remember that time loses all conventional meaning once you pass the event horizon. Now compare that to what we think we know of our own big-bang... that we believe all matter started as a singularity, and that in the initial expansion both time and the very laws of physics were quite muddy and took a bit to settle into what we know today. Within the black hole we don't even know if the concept of matter still has the same meaning -- what appears as a known value of X suns to us could resolve to a whole universe if the physics change.
I'm curious why you think the matter coming it to a black hole would be observed are rushing towards the singularity? We've already seen just how insanely that much gravity distorts the perceptions around the outside of a black hole, so why wouldn't the same be true on the inside? Our own universe has a finite amount of matter, and yet the space it is 'contained' in wraps around on itself so there is no center. The boundary of a black hole could potentially create the same result -- a threshold that we could never cross, but also a wrapping of the space within back onto itself. Also consider the unknown nature of time, what if all the matter that will ever be consumed by the black hole feeds into that singularity while simultaneously exploding into the life of a new universe? In a place where time doesn't exist, all of time would happen simultaneously, so from another viewpoint the billions of years (not trillions) that comprise the history of the life and death of our universe could happen all at once. We know that as we look back towards the time of our own singularity the math surrounding time and space break down to a point where they no longer have any meaning. The same is true for what happens inside a black hole, it all breaks down and become meaningless under our current math. Until we know more about what is happening, or find some way to peer back before the big bang, you really can't discount the idea that what happens inside a black hole could be similar to the creation of a new universe. What appears to us as stringification could be the result of the math showing us the entire history of a moving object instead of a single point in time. Hell we don't even know if time works the same way, maybe once you cross the event horizon time starts moving backwards and what we see as everything moving towards a singularity appears in there as a universe expanding away from it.
Yes all of this sounds like fantastical sci-fi stuff. Then again, what we know about the birth of our universe and how space and time are warped within a black hole also sounds like fantastical sci-fi stuff, and until we have a better grasp on the nature of all of it, there's nothing yet that proves or disproves if a whole universe could exist inside a black hole.
Yeah I agree that we shouldn't try to contradict the evidence we have without a good hypothesis to back it up, I just feel like we're still at a stage where the mathematics give us an idea of what might be possible, but that is seriously constrained by our limited understanding of what happens at these grand scales. Without letting your mind wander to the possibilities of what could be, we would never take the time to look beyond what we know. I'm just trying to say that our knowledge of the subject is still greatly limited, and this idea can't be ruled out completely until we know more. In the meantime, what if someone did seriously explore the notion? Perhaps they'll find proof that shows it can't be possible, but perhaps they might also stumble upon a idea even more fantastic.