I would blame UX there :) In my mind a collaboration tool should not be a burden, if people let it down, it means it's not appropriate. Hence the success of Slack: people realised collaboration can be made easy and real-time without being a pain.

And wrt self-hosted chat servers, you can have a look at some implementations of Matrix (http://matrix.org): there is an opensource a ref implementation of a server (https://github.com/matrix-org) and then a bunch of clients at different level of glossiness, for web, iOS and Android (http://matrix.org/blog/try-matrix-now/) available. Or you can build your own if you feel like it :) Fully decentralised and persistent communication.

No full blown collaboration tool but public & private chat rooms with the ability to exchange files and do 1:1 voice & video calls (group call is in the pipe).

I'd say it likely is a culture problem, the first thing all our developers, project managers and engineers do when they get to work is login to the chat server. Everyone has their clients (mostly Adium with a few running Pidgin / Empathy) set to auto-join a couple of rooms, we have one called #devops that most people join and then one per major product that people may be working on.

ldap, works like a charm