I have many older Bals, mostly Cities and Days, and have not experienced leather cracking. I wonder if you are referring to the wear on the bottom corners of the piping? This can be a problem on the bags with corner piping, but can be minimized with a little care about how you handle your bag. It is fairly easy to be aware of not scraping these edges when setting the bag down, going through doorways etc. Some of us take the added precaution of coating the four corners with various invisible products for added protection.
You mention the glazing, and I think you mean what I call edge coating. That can get cracked on bags like Cities, Part Times, not so much Firsts. It seems to happen when bags are filled fairly heavily, and carried primarily as shoulder bags with the long strap. When carried that way, the soft leather bags bend in the center, putting a crease on the top edge coating, eventually causing it to crack.This doesn't happen to Cities and Part Times that are carried by their handles as totes, or even with the handles over the shoulder. I think of it as a design flaw, as the straps attach too far apart. The Velo doesn't have this issue as it is narrower and less likely to bend in the center.
Not sure if I understood your concerns, but I think of these bags as appearing deceptively fragile, but being tough enough to look great after a decade of use. If fact, there are multiple threads here attesting to the way age has enhanced many of them. While not completely care or trouble free, to me they are so beautiful and special, that they are worth a few simple precautions.
Obviously, I'm biased, and I do hope you decide to take the plunge. Most of us who buy one, want another.