First, let me thank you for adding the Width in the latest update (2.21). Much appreciated!
We need a fixed height for our text areas to encourage user-interaction and ease the UX for the end user. Having (now a wide), but very narrow description field is not ideal and since it's basically a feature of HTML5, I don't see why it be exempt from Blazor UI.
<TelerikTextArea Rows="10" Width="100%" />