Every animal model is imperfect and the various tools to try to address them (e.g. greater genetic uniformity) have consequences as well.
If you pick the wrong model your research will fail. Even if it gets through the pure research phase, the FDA will want justification as for why your animal of choice is appropriate.
I had a program that required — ugh — guinea pigs. Those suckers ended up costing $1K when all was said and done (not the cost of acquiring them,but looking after them and running the program). Rats would have been cheaper and mice even more but theOr immune systems could reject the pathogen we were trying to treat; the GP was the least expensive animal it would attack. (There turned out to be other advantages too but that was that for research). And when it came time for the preclinical work for IND submission the agency wanted an EMEA more expensive animal because it was a better human model.
So it’s an engineering trade off, just like any other. One controlled for when possible. Sorry there’s no conspiracy.