There are a bunch of pro's to having an officially acknowledged Toribash Discord.
First off, it's one server instead of a bunch of unofficial splinters. Because of this, it will be more convenient for players to find the server as permanent links will be provided from official Toribash sources like the news board, #support and #toribash channels in IRC, and probably a bunch of other places as well. Confirmation that it is indeed the official server in itself will also get more players involved.
A Discord server is not hard to set up. Perhaps current IRCops could set something up. This way you can be certain of professional moderation following Toribash guidelines. If you don't like the fact that staff will get influence on Discord, please remember that you are free to make your own side-servers whenever you like. No one will be able to tell you you can't.
Discord is a huge improvement over IRC. Discord is now one of the most accessible chat services for gamers. Many people use Discord, and you don't need to set up much client-side, unlike with IRC clients. People joining for support also don't need to install Discord per se, because of the web client. This is kind of similar to webchat, but unlike webchat, you get all of Discord's features in the web client except for maybe the in-game overlay. The in-game overlay, by the way, is one of those features that makes the downloadable Discord client worthwhile, because you don't have to exit your game to ask for support or chat with other Toribashers. Another thing that makes Discord great is that it has a mobile app, so you can stay in touch with Toribashers on the go. With IRC, this is a bit harder, because everything you miss while you are offline is gone forever.
The fact that IRC would become obsolete was inevitable. Discord and IRC can coexist, and surely will, but the modern platform for gamers is Discord. There's no point in being conservative with the community in terms of media used, because you will only make it harder for new players who haven't been around for long to adapt. And you want those new players to get involved in order to be able to maintain a healthy community.