I don't believe I used the word "many" (in fact, I said "not that I've owned a lot of Shure cartridges"), but I can see how that impression was given. The other Shure cartridges I've had include an M70BX (for a Stanton STR8-80 turntable), M44-7 (used on an old Dual changer, along with stylus for 78's), M44G, M91ED, and a couple of Radio Shack variants. All were pleasant, just not terribly engaging. I tend to buy cartridges at least once per year, and have tried various models from Pickering, Audio Technica, Grado, Empire, Goldring, Stanton, ADC, Linn, Sumiko, and Micro-Acoustics. I still just like a change every so often, but I keep returning to Stanton as my cartridge of choice.
For a while, I thought I was done with Shure, but the VST III was purchased just so I could buy something from a friend who worked at a hi-fi shop (and who was a big Shure proponent). And a couple years ago I bought the M97xE on a whim shortly after that friend died. I was expecting another pleasantly inoffensive listening experience, and was surprised at how musically engaging the sound was.
From comments in this thread, I see I'll need to keep my eyes out for one of the V15 models to try out as well.