I do believe in increasing personal responsibility of people and having less of a nanny state, so I do tend towards that answer, but it's really not that black and white. On highways and places where pedestrians and bicyclists are not allowed - yes, no speed limit makes a lot of sense (and is available in Germany for example)

In cities and suburbs where kids can run into the street in unexpected places - more thought is needed what is the best solution.

I've actually gotten a speeding ticket because I was going 35km/h in a "construction" zone with a temporary 30km/h limit on a freaking Sunday with nobody around. That is also clearly ridiculous.