The regular expression based virtual uri mapping is very often not sufficient as one has to predefine under which location a certain template (product catalog for instance) is used.

/products/the-product.html --> /products.html?product=my-product

Todays workaround is using the selector which leads to ugly page names= /products.my-product.html

In Sling they use extensions to solve that use case: /products.html/my-product

In my opinion this is a rather a nice solution to that problem.