There are still people out there (such as myself) and very tiny amount of game studios who still care about these small details and will often rewrite movement from scratch in their respective engines. To me, fluidity of player movement should be very high on the priority of "features".
You are quite right though about devs just leaving UE movement...which is a huge shame because it's a such an important detail in a game; how the game feels. I don't blame devs who don't do this though because it's incredibly complex to write your own especially around what's already there (10x so if you're doing multiplayer); I've also come across whole studios while contracting who don't understand that having a game that looks good but feels bad can impact their sales/reviews.