On the branding: As much as engineers like to say "Engineers don't give a toss about branding", I really think we do. We are less susceptible to it because we (like scientists and researchers) are trained to look at facts, but we are still human. All of use will give pretty things a little bit of a positive bias, things that aren't will get a negative bias. Part of the reason why peope see vendors like Analog Devices, Linear tech, or T&M brands like R&S, Tek, HP etc as "reliable" is because they have nice, organized websites, datasheets, ... It's consistent, you know how it looks, it feels "well designed". It's one of these things we don't notice when it's done well, but we will find blatently obvoius when it's not. (ofcourse, the main reason why we like them is because they simply are well built and well engineerd devices. Just stating that if they didn't have that marketing, it would take more effort to get there.
There is also the fact that social scientists and behavioural analysis people will be able to write entire books about how the look of something influences our mindset. If you have nice "light" documentation, with softer colors, it will make you feel more relaxed when looking at it. By being hapier, you will automaticly be more positive towards the data inside.
Then there is also the fact that the marketing material gives an image about the company. If the material is neat and tidy, consistent, it gives a good image: They seem to have attention for details, they are organized, ...
Let's face it, who here hasn't gotten a datasheet from a company that looked very poorly done and gone "hmm, can I really trust this brand? This documentation looks quite crusty..." Even though it might have been the best built, highest performance part on the planet!
Oh, and as others have said, that stuff also matters a lot towards the investors...