If someone is drunk driving in a Toyota Yaris and runs a red light and smashes into me, I'm not going to shed any tears that my big heavy SUV made it unsafe for them.
If anything, I'd suggest doing 45mph on a road where there's the possibility of a child walking into the road faster than you could respond is irresponsible. If you're going that fast in a built-up area, you should either have a good enough view of the sides of the road that you can see the hazard developing in good time to react/break (ie, you're tracking the pedestrians alongside the road a hundred metres ahead of you), or you should be slowing down to a more appropriate speed for when you're lacking situational awareness.
I suspect this is a large part of the reasons that some countries (eg, the UK) have a hazard perception element to the driving test.
This is a perfect example of prisoner's dilemma - everyone would be safer if everyone else was driving smaller cars. But because people are optimizing for their own safety everybody ends up buying large cars.
In the end, nobody is actually safer, and there are tons of negative externalities caused by everyone driving large cars (increased fuel consumption, road wear, significantly higher risks for pedestrians and other road users, etc).
[1] https://insurify.com/insights/car-models-most-duis-2020/#1.-...
This claim needs a source, and the article does not provide that.