Photography

You’re entitled to your opinion about the interface (I personally think it’s quite sleek, especially for a user coming from Lr or other simpler editors but not wanting to get into Dt-levels of complexity), but it’s not intended to compete against Darktable in the first place. I would argue that it looks more like Adobe Lightroom (its actual competitor, as stated even in the developer’s ReadMe) than anything.

Keep in mind:

• Adobe Lightroom is the lighter, more streamlined editor with more of the ease-of-use. This is closer to what RapidRAW is trying to achieve. This is shown in the more lightweight interface with fewer options and controls.
• Adobe Lightroom Classic is the heavier, more powerful editor that tries to have all the features. That’s more of Darktable’s area. This is shown in the more detailed interface with more options and settings.

↑ LrC vs Lr interface

Not everyone needs both programs – most people would probably be fine with just Lightroom and don’t need the power/want to deal with the initial complexity of LrC. For people who want those programs without the Adobe, however, that’s where RapidRAW and Darktable come in.