Demanding "harsher penalties" is a typical populist attitude, no matter where the bar is set. The public perception will always err on the side of thinking that the system lets people off too easy. However, I've actually served in the system, and my opinions are based on actual knowledge of what happens, and not just the newspapers and their attempts to create fear.
Or, to actually make a point and not just rant, our system has slowly become the most lenient in Europe, and Green do-gooders keep shutting down prisons and creating artificial systems for cutting down the sentences given in the name of "savings". (first time in prison, non-juvenile, serve half of given, already generally rather short sentence, repeat offender 2/3s, become first-timer again after a couple of years etc.) People given life sentences, known to be dangerous, are released and then execute three people at the McDonalds drive-in within a month or two... and so on.