One quibble, though, in fairness to CCP: there’s no way to simulate real-world loads on a system. You simply can’t test having 30-50k people all using a chat system simultaneously, because real-world people behave unpredictably.
I do think the chat client is a mess, but a lot of it is limitations of the technology itself. Like almost everything about EVE, it’s an extraordinarily demanding system that doesn’t really have anything comparable in other games.
And let’s not forget that the old system brought with it socket closures, lag in high-traffic systems, and a lot more server load that impacts game performance. I’m not sure I’d want to go back to that.
TL;DR: the current chat system is the worst, except for all the alternatives.