Why mention town and country of equipment manufacturer?

I think this is especially common in the medical literature. The objective, as you said, is to make sure readers can find the exact same product you used to get the full picture and for the purpose of evaluating or reproducing your work.

Even in the "Internet age", there are many reasons why one might need the physical location of a manufacturer in order to access their products. Here are a few that come to my mind:

• Many companies are not easy to locate with a google search and I know several that don't have a public website or any sort of web presence at all. It might feel silly to write "we used Gmail (Google, Mountain View, California)" but there are many businesses that are not as publicly known. If you're looking in an online phone book you still need to know where to look for.
• Companies might have many subsidiaries and divisions that could be developing products and prototypes without the other ones necessarily knowing about it, especially prototypes. Contacting the wrong one might lead to a dead end.
• Due to different regulations (and that is especially true for drugs and medical equipment) it can be that the same company is selling different products depending on the location. The exact composition of a drug or the firmware might differ depending on where the products were sold.
• It actually sometimes happens that two completely unrelated companies providing the same type of services or goods that are active in separate countries have the exact same name. Confusing, I know.
• Companies disappear, get bought, change name, etc. Knowing the location at time t might help locate the new entity that could deliver the product.

This being said "the journal wants it" is a valid argument, if it's effectively the case and "everybody does it this way" is not that bad of a reason when it comes to article structure and writing practices. Be creative on the content, not on the form. I personally don't feel brackets with (Nvidia Corporation) "break the flow" less than (Nvidia Corporation, Santa Clara, California).

Plus it brings back good memories of time spent in California.

I've always assumed that this is in case there are two different companies with the same name. The location of those companies will almost certainly remove any ambiguity.