Joomla itself is not responsive, and that is great.... because it doesn't have to be responsive, but it can be made to be responsive with templates.
Even some of template clubs still use joomla1.5 as their main webpage but with responsive features, not bootstrap......twitter can change their class names as they wish and they have done so in the past, then it will be mess...but twitter is not the subject here.
I am a customer. As such i am not satisfied with limited "responsive" feature in hikasop, beacuse, obviously, it is limited to be used with bootstrap template only.
I feel neglected because i am not able to use responsive feature/option of hikashop on existing webshop which uses joomla2.5 responsive template.
Responsive feature should be universal, and not limited to template type, so all serious paying customers can be pleased.
BTW: Tienda has great potential, but development is not near production ready, and only God knows when it will be, if it will be...you cant be serious if you tried to use it in production enviroment for ecommerce.