Slacks growing usefulness is predicated on the fact that people build bots for it.
It's not that IRC can be as good as slack -- IRC is NOT the same kind of thing as slack, they are different. IRC is a protocol, slack is not, slack is a product. My point is that the right product needs to be build AROUND IRC to make it viable/interesting.
From the previous comment, it seems like the features people are loving slack for are:
- Well designed interface
- File sharing
- Inviting/sharing channels with people
- Functionality provided by bots
Is that incorrect? I'm sure that list is incomplete, is there anything very significant I left off?