I don’t like the presentation of D&D 5e. I particularly don’t like the art. If you’ve read There is an aesthetic that I want and a way I want to feel, this may not surprise you. But I can see its properties support the aims and desires of the creators and their audiences.
The key challenge for 5e is appealling to a very wide audience. It’s going for the broadest possible market share, and has a wide range of player groups who consider it “their game”. It’s not a niche-niche game, at least not compared to LotFP or Vampire or Burning Wheel.
And of course its owners want to get money out of it, or at least to maintain brand value that they can use elsewhere. And the fan base has diverse interests and values
First, some simple good things that are compatible with the aesthetic I’m describing:
- Diverse ethnic and gender representation
- (e.g. they represent “human” by a black woman who looks tough and is not sexualised)
- The organisation of the text, the typography, and the graphic design are all very clear.
- Their way of describing rules is very precise and consistent. It’s too precise, and too detailed for my liking, but there are advantages to pedantic precision.
Then, some things incompatible with my aesthetic, but that have other benefits:
- Colourful, attracts the eye
- Generally controlled and competent — doesn’t ever look very clumsy
- Consistent with what a lot of people like – cf many video games, comics, and their associated fan art
- Implies a fairly wide range of possible settings, in both environment and costume
- (this is common to most generic system, and I find it off-putting — FATE and Hero Quest have the same problem)
- Inoffensive to the vast majority of people 
- Broadly suitable for children, even in the eyes of fairly censorious parents.
- (And most adult owners will be happy for their children, of any age, to flick through it. So it can go anywhere in the house)
- Not upsettingly gory or painful for almost anyone.
- (Issues around this are killers for a fair few people. And even I, despite my commitment to things with extra tubes, won’t watch e.g. Saw or The Human Centipede.)
- Possibly the background pattern has some anti-piracy value, making copies harder to print, or at least more expensive 
 Exception is a certain class of bigot. But I think most of us can live with that.
 Though may be a problem for people with limited vision? Though a comment on Stack Exchange suggests probably not.