Absolutely. If you want top-tier results, you'll have to hire top-tier people and I don't know a single "designer" who's great at every aspect of design and front-end development. It's important to realise that great design is a balancing act between all these aspects and to ensure your team manages them, e.g. a designer designing isolated from the front-end developers.

If you're not hiring employees, but are relying on freelancers, I question just how reasonable it is to have a designer use your templating languages and other tools instead of standard ones such as plain HTML and CSS. There are exceptions though: things like Wordpress and jQuery are common enough that you can easily find freelancers who'll be able to use them (but they're not common enough that every freelancer will).