Not understanding your underlying conceptual model (be it biology here, or maybe healthcare, or natural resource exploration) will lead a lot of poor assumptions, limiting the impact of all the hard work.
That is when performing a test on a mouse we are not measuring what a particular mouse would do, but what the mice do on average. So as long as model behaves like a mouse it can be useful, even though it would not behave like any particular mouse.
Also it's important to remember that the question is not about all or nothing, when we get a model most likely instead of 100 experiments on real mice we will be doing millions on virtual mice, and then 10 on real mice to verify the results.
The Game Of Life seems to contradict this claim. Also worth considering, computational physics and weather/climate simulations.
Scientists of all sorts already do learn new insights by creating simulated models of systems. The simulated systems will continue to get more accurate.
If you didn't have at least a broad idea of why something might work, you would most likely never have "done the thing". You need to narrow the search space. Simulations can help here.
Programs and algorithms can only encode models (which are themselves imperfect) of what we already know. There's countless things we know that we don't know, and yet more that we don't know that we don't know.
As bad as animal (and human) studies and trials can be, the beauty of them is we don't really have to know how or why things work, we can just do the thing and if the results are good, we have a new treatment. Lots of super common drugs, even paracetamol, are like this.
Of course, knowing and accurately modelling the action is great, but it's not necessary.