WordPress blog posts need to be in Widescreen 16:9

Websites like YouTube now display in Widescreen format and YouTube embed videos that wordpress users embed into their blogs are in Widescreen 16:9 format so when embedding these videos into wordpress it makes the blog post look cluttered.
Wordpress should make the blog post support Widescreen 16:9 embed videos and not make it look cluttered.
The video pixel size for a widescreen youtube embed video is 640×505 and the lowest widescreen pixel size is 425×344.

Do you think you could change your default themes to this wordpress?