Digipiction
There's nothing wrong with the UI in its current state
Lots.
animatrix_
Stowing bars is very useful as well as getting rid of a lot of large UI items like shelves. It can make a massive difference on laptops.
Always a crude patch.
So the to translate the op's question...
Everybody seems to be hiding the shelf? Why? Because it's horrible, and everybody keeps bashing c4d, granted it's a toy compared to houdini, however c4d's ui mechanics and consequently ux (prior to R25) were second to none.
Don't tell me that no one here would not welcome a customizable "pallete" that can host buttons and from that buttons dropdowns and that is also dockable anywhere, which would mean that you could customize eg. the shelf to take up less space while also being readable, or remove it completely, with the ability to bring it back without going to the prefs folder, you could also customize the right and left sidebars so that for example the flipbook button would actually use a better offscreen opengl renderer, sure you can make your own, but why is that button there then, it's quite stupid.
Panels could and should be "dragable" drag to undock/dock or move to a new location instead of static hit and miss current one, while you pray to whatever deity you believe in for houdini not to crash.
No one here would welcome a neatly padded parm panel that does not make fields go out of bounds, with improved readability, or thought out spline ramp, c4d's ramp editor is light years ahead in every way, or the ability to define color fields to default to HSV instead of RGB or whatever other mode suits the user since rarely would you input the exact rgb value.
Or how bout a better ladder or better yet complete removal of it, since it's more trouble than it's worth (unless all you have is npoints(0)<1), or a button next to vector values to lock them to uniform instead of constantly referencing and deleting, or better mechanics of saving and organizing vex snippets, or the not so finicky transform gizmos, or the auto near/far clipping planes that work always, or spline drawing tools that are actually useful and easy to use, and by easy I mean less time consuming (which is what most people mean when they say easy in context of DCCs, or attribute selectors that add and remove values, or better, by default, ui centric, save, autosave, backup and versioning that guarantees no scene corruption, detecting and loading of scene files from backup, better organized and more useful right click menu (by default)...
Well this got out of hand quickly...
Or maybe he did really just mean the ui visually!?