Your customers might have different search terms to that in your title or description. Tag search would help this.
I agree with you, Search by Woocommerce Tags is one of important feature.
Why this isn't a part of WooCommerce is beyond me. This would be a great addition to Flatsome search. Most of our shops key terms are within the tags. When you have many product variations, tag search would really help. As it stands, our variations will not return in search results on our site. Only terms within the title have a chance in site search. Not very helpful for the user/customer when they're trying to narrow down choices or find exactly what they're looking for quickly. Plus 1 here!
And shows the "sku" on the Search results