Out of the box you get:
1. 1-on-1 messaging
2. Private and public chat rooms
3. A client that works on mobile, desktop, and web.
No matter where I am, I'm connected to my team.
4. Persistent and searchable history.
5. Real-time notifications if someone mentions
you while offline.
6. You can copy and paste screenshots directly into
the room. We use this all of the time for gui
mockup discussions.
7. Integration with most online services like
GitHub, etc...
8. Easy file transfers.
9. No servers to manage.
10. Easy user management.
11. Video calls.
12. Voice calls.
13. Screen sharing.
Most importantly, it all just works. We could get IRC to do much of the above, but it'd be a hodgepodge of a solution and require someone to spend time setting it all up and maintaining it. At $2/user/month HipChat is a no-brainer. Why waste engineering resources trying to solve problems that someone else already solved for us?Edit: And custom emoticons. Can't forget those. That's the best part of HipChat.
I'm sure it's possible to get that setup with XMPP, and it's definitely possible to get an equivalent setup with IRC (which I have an external server running ZNC for), but it's not out of the box, and there is something to be said for having a good configuration set up and working for everyone out of the box.
Persistence also allows you to search through or link people to old conversations.
Does every product really need a technical justification? If every person at your company is comfortable setting up email clients, IRC bots, and bouncers, then this isn't a product for you.
If you would rather just pay someone $2/person/month to set this up for you, then this is the product for you.
Just last week we onboarded a new developer and instead of having to spread her personal GChat address all over the company and make sure that everyone has authorized her to speak to them, and worked out the kinks for the few (like me) who run their own XMPP server that play russian roulette on whether Google is going to allow federation today... we just sent her a link to a URL which allowed her to create a user and immediately started downloading a client that once authenticated, connected her to the entire company.
Granted, we could have used our internal IRC server (we actually do have one set up), but the maintenance behind it really started to get to us. In order to use it we had to VPN in and connect, and backlog wasn't available to people that aren't technical enough to understand shell clients (like our project managers). When we did decide to open up the security permissions we had spam bots connecting 24/7 trying to get into our channel, which we then had to password protect, which ended up being another piece of tribal knowledge that "you just had to know".
Still, I continue to have Campfire (Flint.app), HipChat, Adium with XMPP for OTR, Google Hangouts for multi-person conferencing, Email, irssi and Twitter open all day. I wish I could consolodate them all into one, but I can't because they all have specific use cases. If HipChat was to allow an OTR plugin and multi-person video chats and screen sharing, that'd get rid of 4 of my communications^W daily distractions, but it wouldn't get rid of all of them because they serve different purposes.
At the very least, HipChat being free is a much better argument against using Lync now.
There are a plethora of IRC clients to choose from one various platforms, but there's only the one hipchat. IRC is also an open protocol.
So, hipchat's only real chance is trying to be the Apple of IRC--they must nail UX and marketing to the tech-hapless to have a real chance.
however, for the rest of the world, if you work with a non-dev team (think sales, marketing, customer support), you will really frustrate them when you tell them: "the question you just asked was answered at 3am last night, if you just scrollback..."
...god forbid you lose power (like san francisco in a heat wave last week)
or you could just choose to really frustrate your IT person(s) by telling them they need to install and maintain irc clients + bncs across multiple operating systems for your users, that automatically start up and join the right channels when the user logs in.
or you could just frustrate all of your mobile users by draining their battery (and potentially their data plan) by telling them to stay connected to irc 24/7 from their phones via a mobile irc client, or hold a companywide training session on how to install an ssh client + screen-reattach + navigate irssi from a touchscreen phone.
or you could further frustrate your users by telling them irssi includes search as long as they learn the syntax of /lastlog.
i'm not even going to touch screenshots.
user-friendly > neckbeard.
pay the $X/mo per user for slack/hipchat
-versus-
paying $XX to $XXX/hour per user to provide them with the requisite knowledge foundation and ongoing support to use your arcane chat methodology that hates noobs.
I wish IRC was overhauled SOMEHOW and made more accessible to the common person.
It's no more difficult than browsing the web.