The RichTextArea.setRows() API was there in the older version but really had no effect on the RichTextArea. Setting it to 10 or 50 renders exactly the same RichTextArea as when not setting it at all. If you would like to see that RichTextArea had a setRows, please create a ticket at http://dev.vaadin.com. The difficult thing is to say how high a row is as the RichTextArea contains rich content with possibly varying font sizes, embedded images etc.
Please note also that TextArea and RichTextArea are not the same component. TextArea (previously TextField using setRows) still supports setRows like before.