Are you looking at equivalent versions of each motherboard?
If you look at an Asus P8Z77V-LX vs an Asus Maximus IV Extreme then yeah there are differences.
But comparing similar boards side-by-side there is actually very little difference in features.
MSI GD55 and Asus Pro, Z68 (Gen3) vs Z77 comparison here.
This seems to be the case. Although, I wouldn't say they've taken a step back, considering X79 was for the SB-E procs like the 3960x. Z77 is for SB and Ivy, if you catch my drift?