I know it's not particularly uncommon for web sites these days to drastically change things and in fact most people consider this a feature. The fail fast mentality is great and all except that it means you are often failing more than not and the general consensus seems to be that it's perfectly acceptable to do it in public to the detriment of your users.
To move from a general rant to something slightly more specific here are a few examples from the latest YouTube redesign that really drives home the level of amateur hour that keeps infesting the web.
This video was not vertically letter boxed
I know CSS is hard, but come on Google...
Yes, I always wanted to scroll left and right to see my whole video
Insert sad trombone here.