I do PCB design, mostly in Altium, and I'll even add that some of my designs are of relatively high complexity.
Saying that Kicad interface is horrendous compared with Eagle is, to say the least, disingenuous. Eagle has a terrible interface, lots of limitations, and a very strange mental model for design.
Kicad is still far from perfection, and I do believe that the UX must improve. But even the best tool in this aspect - IMO, Altium - suffers from a lot of other issues.
That's a good comment. There are two basic classes of UI problems with KiCAD. First, there are the ones that are just classic menu-and-button bad design. The schematic library and footprint library editors have a confusing set of menus and buttons to do what's really a simple open/close/new/save task. There are lots of discussions on forums about this. Those need a rethink of the library UI, a clear design document, and a modest amount of implementation. If that got fixed, the initial KiCAD complaint level would go way down.
The second set of problems is harder. They're in the programs for graphical design. There are four of those - schematic drawing, schematic symbol design, board layout, and board footprint design. Schematic drawing isn't too bad. It has some strange bugs - there's a convention in schematics that you put a dot where wires connect at a 3 or 4 way connection. (Wires which just cross don't connect.) Most schematic drawing programs handle this automatically. KiCAD almost does, but it's possible for a connection dot to become detached from wires, or for wires to connect without a connection dot. This might result in a bad netlist, which matters. A few bug fixes there would be enough to fix up that part of the system.
The schematic symbol and board footprint editors are just really clunky draw programs. They work, but lack basic features such as grouping and cut and paste. Those wouldn't be that hard to fix. Fixing that, plus the library editor UI, would help the project a lot, because KiCAD needs a bigger symbol and footprint library, and you want users to contribute those. Frustrating contributors hurts the project.
The actual board layout program is the hardest problem. Others have written about this.
There are some very strange features. There are three graphics modes (classic, OpenGL, and something else). Menu items which have nothing to do with display, such as component auto-placement, change with the mode. You can't automatically spread out components in OpenGL mode. The menu item just isn't there. (Not even greyed out, just gone.) There are also some functions hidden in dialogs under menus which ought to be more visible.
The "Help" menu item just loads a PDF of the tutorial, which isn't too useful.
All this stuff is fixable, but probably not via "hackathons". A UI design document is needed. That's always useful; when the UI design document has to explain some badly designed feature at great length, it's clear there's a problem. Write down exactly how all the schematic symbol and footprint library update functions work, and the mess will be revealed.
Maybe it's because I haven't used any other packages, but I've used KiCAD and love it. I haven't found the tool itself especially hard (although there were a few Wtf moments at the start related to the different graphical modes having different capabilities), but, overall, 95% of the curve was learning the actual design principles, rather than the tool.
It took me a few hours to go from never having used any PCB design programs to a simple finished board with KiCAD.
People who design PCBs will probably wonder when KiCad is going to fix the horrific UX bugs, and go back to using Altium or Eagle in the meantime.
KiCad is the StarOffice of the PCB design world. I want to use it, but I can't justify the time working around KiCad's UX issues.