Firstly, Barney Grumble, I think it's great that you have personal vis minima, though I'd make it a bit more flexible for the task as one of the posts suggests.
I would like to give you a perspective from a flying instructor and ferry pilot. For us, particularly the ferrying, we need low VMC minima if we're delivering to an airfield without approach aids. In fact, the CPL VFR minima goes down to 1.5km in class G below 140kts and 3000ft. Once you get the appropriate experience (and, of course, the ratings to know you can get in somewhere else if you have to), 3km vis is actually not too bad. Looking out for aircraft is an issue but a RIS can be a big help in that weather.
For private flying I probably wouldn't bother in vis like that because I want some fun and low vis would be too much like work. However, it is definitely worth going with an instructor in bad vis and learning implicitly to trust dead reckoning - it always works. From my experience, I'd say the biggest problem with poor vis is terrain and familiarity with the area helps.
For low hour PPLs, particularly without an IMC/IR, your minima are a good personal discipline, but I wouldn't want to lift the VMC/VFR minima to suit low hour pilots. The course is designed to help pilots make their own decisions and it sounds as if your instructor has done a good job with you.