For me it's an aesthetic thing, I think the lettering is just so ugly. Same with the orange on the turn signals and brake clusters (yeah old school).
I'm gonna get controversial now though, and say that I'm not really a huge fan of Subaru. I love their engineering, the Impreza is an awesome car (even if the new ones don't look that good), and the rally tradition is great. Subaru really is a living legend in the rally scene. I don't like any of the other cars the company makes though, I think their advertising campaigns have always been poor, and the company has a negative outside image. Face it, it's the truth. I love my RS, I can't imagine owning any other car, but I think the letters are ugly (on any car), and I like when people don't know what I'm driving.
Oh, I forgot, I really don't like the name Subaru either. It's just not very appealing. I don't think very many car brand names are very good though, I think the Germans have the best names, BMW, Audi, Mercedes, etc.