1. Most people I know like Github's UI, so it makes sense to copy it. MS Office is not known for it's UI experience. So it doesn't make sense to copy it.
2. Creating a good UI is hard work. When you're Apple, you have the resources to throw at iWork. An open source project doesn't have the same resources, and they might spend a lot of time to end up with something worse than Github's UI.
To me it's a simple decision:
1. Spend a lot of time and end up with something that could be better than Github but will probably be worse OR
2. Spend little time to copy a design everyone is familiar with and likes.
I think a better analogy would be Gimp vs Photoshop. Supposedly Gimp can do almost everything Photoshop can, but what % of designers use Gimp? They have been slowly moving towards Photoshop's UI because they now realize how much of a factor that plays in adoption.
1. Most people I know like Github's UI, so it makes sense to copy it. MS Office is not known for it's UI experience. So it doesn't make sense to copy it.
2. Creating a good UI is hard work. When you're Apple, you have the resources to throw at iWork. An open source project doesn't have the same resources, and they might spend a lot of time to end up with something worse than Github's UI.
To me it's a simple decision: 1. Spend a lot of time and end up with something that could be better than Github but will probably be worse OR 2. Spend little time to copy a design everyone is familiar with and likes.
I think a better analogy would be Gimp vs Photoshop. Supposedly Gimp can do almost everything Photoshop can, but what % of designers use Gimp? They have been slowly moving towards Photoshop's UI because they now realize how much of a factor that plays in adoption.