Every Instances(Servers) should have distinct UI appearances not only logos but also background, colors, typefaces, layouts and so much more, so that they'll remind me easily that I'll be at a different instance. It might rouse me more to lurk like travelling to any other dimensions. Js
The idea is that there is not only one big instance, but various instances that compliment each other. So the current cap of Lemme.world is around one million users according to Ruud, one of the admins. In that case, we need other intstances to make this work.
In fact, I suggest the opposite. Make it look the same, remove the branding from Lemme.world and name it Lemmy, everywhere. The url does not matter to the most people and can cause confusion. Fediverse is already busy inplementing a more seamless experience, such as the merge for sublemmys on different instances.
The concept should be easy to understand. As of right now, the Lemmy concept is not hard to understand but for the avarage Joe it can take some time to get used to.
It will come. Current theming options were disrupted with the move from Bootstrap4 to Bootstrap5, but once things have stabilized on version 0.18 we will see lots of nice Bootstrap5 themes I think.