Well obviously weight matters, you get reminded of that every time you go up a hill, especially a steep one. So how to determine the trade-off between weight and utility? This is all about the type of touring you're doing. Andrew and Friedel (Avatarworf) are way too savvy to carry more than is appropriate on their tours but they carry more than most of us -- because the touring they've been doing all these years is what might be called expedition touring. If they were on a weekend tour like the OP describes, I guess they'd go a lot lighter. Ditto a month riding around Holland.

The right weight is what suits a particular tourer on a particular tour. As you get fitter, the 'cost' of carrying a few more luxuries diminishes -- shifting the trade-off. As the tour gets longer (eg. from three seasons to four), some of the luxuries become necessities. There seem to be a lot of criticisms on this forum of tourers carrying too much or too little -- usually without taking into account the specifics of the tour or the tourer.