I've been running a CS-Cart store since 2009 (used another cart prior to that). I've never enabled the product tags add-on, and I've never seen it discussed very much on these forums. Does anyone attach any importance to product tags, and if so, can you explain why? Is it supposed to be good for SEO? Thanks in advance for your input.
I don't think it's relevant to SEO at all.
You can have system defined and user defined tags. I.e. a customer can tag your product with 'good one' or something and then be able to find it again in the future.
It's one of those niche functionalities that I think you'll find was “cool” at some point in time but after actual use, it became less popular because people don't really remember what they used as the tag…