I agree with your perspective on what great service is about and its benefits. In my experience, it can also be a powerful differentiator, and it can help to support a premium price vs. more commoditized competitors.
I think that when you really care about your clients, you get to know them and you find out about other problems you can solve for them, or about where they want to go and how you can help them to overcome obstacles to getting there. Finding these things out can lead to product/software improvements or even new product offerings that can deepen the relationship. Or maybe it can just help to ensure your clients are getting full value for their money.
We would all be well served to remind ourselves that when companies decide to buy our services or products, that those decisions are made by people who care a great deal about whether or not we are solving their problems, and that they are judged for how they spend their budgets. We should care just as much as they do, if not more.