You don't need to add yourselves but as it gets traffic that is predominantly customers for your services I thought you might want to.
Google maps are not exclusive so if I was a provider I would add myself to all free google maps. However as I'm not a provider I wouldn't tell you how to run your business.
As for running your own map I didn't suggest it I only offered my code for free.
To sum up. You are free to add yourself if you wish as it costs nothing and gets visited by a high percentage of active customers looking to purchase your services.
You are also free not to
Cheers.