New twitter layout

Twitter has introduced a new layout which seems to makes use of space better. Well, having the timeline to be on the right instead of the left itself could get becoming something to get used to over time. This could affect how I do things.

Why is this the transition more smoothly than during the previous transition in... was it in 2010? I think there was an overall with the code, like being able to view images without opening a new page or what tweet is being replied to. The current new one just needed repositioning of things.