Instruction manuals are often still regarded as an inevitable obligation and cost factor only. As a result, we find many user guides being visually unattractive, hard to handle, hard to read and not reflecting the quality of the brand and product. Think twice about this “strategy”. You could scare off potential customers who have a look at the instruction manual before they make their decision.
What would you think about a product or brand if the user manual doesn't look professional? Would you trust that company? Would you think they meet your demands for quality?
There's also a legal point here. By placing the CE mark on your product, your company is declaring conformity with all of the legal requirements to achieve CE marking. These legal requirements include conformity with technical standards applying to the product. Since the user documentation is regarded as part of the product, technical standards applying to user documentation also have to be taken into account.
IEC/IEEE 82079-1 is the relevant standard for user instructions. Reading and putting into practice the sections about structure, layout and typography before launching your manual can make your customers happier and protect you from complaints or legal claims, especially when you have to inform users about any residual risks.