size and proportion wise, the post that's being replied to is much more comfortable to read than the actual reply to it
whenever someone makes a longer post, i always make some reply to it active, and then read the main post from that view 
Discussion
Why is it more comfortable to read?
padding from the sides, smaller font size
not a fan of full bled text, have to adjust my eyes more and lose track much more often
the first two points were said in a way that i'd like it
brainfart
For me it is much more comfortable to read when it is all the same font but I understand both sides.