Well, keep your happy memories as a treasure!
I have similar ones about the Buttes Chaumont (N.E., 20th arrondissement). This has changed too, and the Park is now closed at night - too much drug dealing going on. As you say, sad, so sad.
I have not heard about this Jazzy, but I think it is a great shame. My advice to any tourist anywhere nowadays would be 'beware of your purse/money'. This was the advice I was given when visiting Sevilla - Had to buy a banana sort of bag (you know, the one you fit around the waist, is it called the same in English?). Main thing though is to wear it under your jumper/T.shirt lest it gets cut off swiftly without you feeling anything.