I have helped one and two person companies become ISO 9001 and AS9100 certified so I know from experience that there is no company too small to benefit from it.
Benefiting from it is dependent on embracing what the standard can do for the company and the employees. Those that embrace it discover that life gets easier. Those that don't embrace it, the ones that try to do just enough to get by, will find that it is always going to be a festering thorn in their side.
Here are some obvious benefits:
You have gained tools that can help you to resolve problems easier and in a more permanent manner.
The entire organization works better together as they are all working together to achieve the quality objectives. One of my clients said it best when explaining why he liked quality objectives/kpi - "because we can't hide things from each other anymore".
You become more attractive to the marketplace, especially as your quality and on-time-delivery improve. This translates to more job security and may indirectly translate to better paying jobs from higher earnings.
It tends to help the company stay abreast with changes that could effect the quality management system (this can include new technology, new equipment, new markets, new customers, new competition, and much more). This depends on how they deal with that particular requirement in management review which is wide open and many organizations try to limit it to internal changes. The 2015 revision of the standard may improve the awareness of this with the new topic in the new 4.1 where it is required to deal with understanding the organization in context.
So, even with just two of the topics, life gets easier and improved job security, what is there not to like for all employees, especially the rank and file, not just top management.
There are two main downsides as I see it:
More paperwork. There really isn't much if any more, and it becomes routine very quickly. When it is discovered that the extra attention to detail provides information to better and more quickly resolve problems this concern melts away very quickly.
Fear of the unknown. People resist change because they sense a fear of the unknown. This also melts away when they learn that communication tends to open up and there is less unknown. It is especially helpful to hold a meeting with all employees near the beginning of setting up an ISO 9001 system and let them know what is going on and why.
When the system is up and running and working as intended it is an awesome thing to see.
Try to take shortcuts and the results will be less spectacular, often much less.