Why do the UIs ignore features already developed on the blockchain?
It would be understandable if only one UI was ignoring escrow transactions and memo encryption but it doesn't make sense for all of them to ignore the features.
If I was to make a UI for the Steem blockchain, I would focus on the features ignored by the other UIs. Product differentiation can result in a competitive advantage.
I don't know, I guess it might be probably some issues with an aggressive schedule, you have an issue here and there, you are quickly late and you postpone for the next release "not mandatory" stuff. May be some missing features here and there to implement it fully, I don't have the whole picture.