The rf2 ui has a ton of big and small issues. But marcel also made a good point in the stream about how you get used to things being the way they are. Like if alt-tab crashes rf2 then you just get used to it and work around it. Same thing with the ui. If you only use rf2 and don't play anything else then for example finding cars from the list doesn't seem very bad but if you come from somewhere else the car list folder labyrith is pretty awful process to find cars in rf2. Just to go through the rf2 gt3 cars means you need to know exact brand and model of each car so you can dig them up from the pile of long nested list. And to add a full field you need to know and remember all the cars... Same thing with adding ai competitors, skins, server browser.
And for mods it is plain awful as well. All of these have really poor usability but if you only use rf2 you have sort of learned to deal with it and do things slower. But if you come from ac or any other game for example where you can just drag and drop to install cars, tracks and skins and it just works or you can find cars and tracks extremely quickly with a simple search or clicking a tag then rf2 feels incredibly slow and cumbersome. Even ams is far superior despite being done of the older engine. And it is not just wrong color of buttons or placement of them. The very limited rf2 structure just doesn't allow elegant solutions to these problems unless you rewrite parts of the engine itself. Rf2 ui can't add tags (gt3, gt3, lmp2, endurance) for finding cars and tracks unless it changes the veh files and its systems or add a new file that actually contains some data about the cars because rf2 does not even have that kind of file! And because every file needs to be packed and rf2 can not into folders you just end up with an unorganized mess that users can not even fix like they can do in ac where you can just open a ui.json file and add anything you want to a car.
I do agree with Martin Fiala. The ui (ui+ux) has been hyped up a bit too much and people expect miracles from it. Same with the new competition structure. Rf2 has a lot of issues and as bad as the ui is it is very much strangled by the underlying infrastructure which doesn't really allow the ui do or fix much. Unless the ui revamp also includes hefty changes to the underlying code and structure then at the most you can expect is slight ui improvements. New colors and buttons in different places. I also find it troubling how much noise is made about the option to not show ai drivers in server browser. This is not groundbreaking technology. This almost a bug fix and the fact that this tiny fix is almost all we know about the new ui at this point is very troubling.
I am afraid a lot of thing is going to be exactly same in the new ui with maybe the launcher and the ui itself merged into one with a barebones function serverbrowser instead of the total awfulness rf2 has now. And last but least any time there is a big change like this in the past it has always meant that the first iteration has a high chance of being even more restrictive and limited than the current ui. Making a new ui is not about just adding new stuff in but also adding the existing functionality in.