None of those things are showstoppers or really anything more than tiny issues - if they are issues at all. You do not need to register with nickserv (it is optional if you want to be a regular and not have someone else take your name) and the commands aren't any different than all the commands that Discord has (some are even the same) - hell, pretty much every other Discord server/channel has IRC-like botcommands that begin with a ! like you'd find on IRC in 1996.
Also i'm not pretending that IRC is straightforward, i'm saying that Discord is as complex as IRC is and adds additional complexity on top of that - sure, some parts might be simpler (though connecting to a new server is not necessarily among them as most IRC clients register the irc: handler with browsers so you can click on any web link to join a server and enter a channel) but those do not negate the complex parts it adds.
And the most important part: the vast majority of people do not use use Discord because it is easier (or harder or whatever) than IRC (or Matrix or whatever), they use it because the communities they want to be part of are on Discord.
Also i'm not pretending that IRC is straightforward, i'm saying that Discord is as complex as IRC is and adds additional complexity on top of that - sure, some parts might be simpler (though connecting to a new server is not necessarily among them as most IRC clients register the irc: handler with browsers so you can click on any web link to join a server and enter a channel) but those do not negate the complex parts it adds.
And the most important part: the vast majority of people do not use use Discord because it is easier (or harder or whatever) than IRC (or Matrix or whatever), they use it because the communities they want to be part of are on Discord.