I worked for a Wordpress host I won't name, and I can tell you that 99% of our installs that had WooCommerce installed also had zero products for sale. The install base is huge, but the number of people meaningfully using the software is a small minority of that huge value.

My experience with WooCommerce is that it's probably the best of a poor bunch if you need a somewhat customised ecommerce site but don't have the funds/resources/expertise to build one on something like Magento.

Because as questionable as it may be resources wise, well it compares pretty well to the likes of OpenCart or OS Commerce, and significantly better than other WordPress shop plugins I've seen in the past (like Shopp). At least you can take your WordPress development knowledge and apply it to templates/plugins, have some decent documentation lying around to fall back on, and don't have plugin developers trying to nickle and dime you for every little thing.

There's probably a market in there somewhere, if someone wanted to actually create a decent ecommerce system that doesn't require a ton of resources, doesn't rely on another system to function and whose community actually knows what the hell they're doing.