Since this is an opinion question you can take it either way.
Pros: - lower speed may cause lower speed accidents, which are less deadly than their high speed alternatives - lower speed could potentially allow people to get lost less often because they are able to navigate and respond earlier <span>- gas savings from optimal operating conditions (between 88.5 - 96.5 km/h [55-60 mph])</span>
Cons: - longer commute times - less enjoyable (if you enjoy driving fast) - may contribute to overall congestion and increase in accidents as people spend more time on average on the roads
Either way, support our opinion and you'll be right.