For some people the car is just another mode of transport and therefore there is
absolutely no need to include car accessories in the things that you secure for the vehicle. For them this represents a waste of money and they would rather spend the resources on something more useful. This is a utilitarian attitude to travelling. I do respect the people that take this route but in the end we have to understand that these play an important part in other situations where you might not necessarily associate them with the product. For example you might find that they remove some of the boredom that comes with constant driving. It might be that those accessories are the thing that prevents a person from falling asleep on the wheel.
There is something to be said for the plain cars that have no accessories but we are all of different personalities. You cannot expect that all the drivers will react in the same way to the vehicle. Some people use accessories in their cars to personalize their vehicles. It is almost a ritual of marking territory and they take it very seriously indeed. You cannot say that their attitudes to these things are not acceptable. In fact the car is one of the private spaces where the driver can have absolute control. It therefore makes sense that they would use the car accessories to imprint their personality on the vehicle. It makes it easier to deal with the road and will make the driving experience an enjoyable one.
The one thing that I will not excuse is poor taste in car accessories. Some people buy some really hideous things and then present them as accessories for their cars. Glaring colours and horrible sounds are not part of the deal. You have to make sure that you take the right sort of attitude to these decorations. They might be excellent for your personality but it does not follow that all your passengers will share tastes with you. If you decide to put on a horror show you might find that people are rather reluctant to travel with you. That would be a pity because cars are generally meant to be shared. On the other hand you might decide that the car accessories are a private matter and therefore you can buy as much junk as you like without comment from your passengers.