Because it's made by volunteers, in their free time, who either don't have the time or skill or goal to make it competitive. But I wrote that a couple of times already and you continue to ignore it. So much for 'not seeing my point'.
It doesn't follow patterns that similar software follows, because they're used to it, so everyone else should be too.
If someone is not able or willing to learn their way around something new, that's literally their problem. Why would it need to be similar? If you want Photoshop, well then use Photoshop.
Sometimes doing something different might also end up being the better idea. Won't know until you tried.
And yes, good software is good code. That's just a fact. Because otherwise you inevitably end up stuck and need to refractor the whole thing, instead of adding new features. And then angry people start complaining how you're not competitive, and oh my.