And yet large numbers of companies and institutions are still failing at it. Indeed, there is a growing perception - as revealed, for instance, in ICL's Lifestyle Revolution report (see below) - that in many sectors customer service is getting worse rather than better.
This may be the result of a number of factors - greater expectations, greater awareness of standards in such countries as the US, and a reduced willingness to make allowances for sectors that are traditionally rated poor, such as banks.
But, according to author and consultant David Freemantle, there is a real problem and its roots lie in the fact that executives leave out the people aspect of customer service. "There's too much glibness and superficiality, too much obsession with measurement and too much inattention to customers' real feelings," he says.
In particular, he says in his new book, What Customers Like About You (Nicholas Brealey, pounds 16.99), the organisations that fail in this area have relied on rules and policies and given employees "no freedom to use their nous".
By contrast, those that are setting the standards - for example, the mobile phone retailer Carphone Warehouse - have "lots of emotional capital and even love", he says. "You can love the product, but equally important is loving people" - whether customers or fellow employees.
It is easy to see how staff can love the product if they are, say, mad about motorcycles and work for Harley-Davidson. But what happens when they are dealing in something with less natural appeal?
Dr Freemantle accepts the point, but says you can either think of a job in terms of going through the right processes, or you can think of it as doing what you have to do to make customers happy.
In the book, he describes how an employee of BT Mobile goes out of her way to create opportunities to please people. Compare that to the resigned "I would if I could, but my hands are tied" attitude that is still typical of many companies.
But employees cannot do this alone. And even if they began with that attitude, in most organisations they would be unable to act on their instincts.
Later on, Dr Freemantle quotes another BT Mobile employee as saying that a few years ago she really wanted to do the best for her customers, but went home and cried because of the constraints imposed on her by managers. Now she has total freedom: "We can please our customers by doing whatever we feel necessary. I can make any decision I want."
The problem with this sort of approach is that managers have to trust the employees who are dealing with customers, and the employees have to build trust with customers, so that this eagerness to please is not abused. For many executives, that is just too big a risk.
Dr Freemantle, who advises organisations around the world through his Superboss consultancy, sees things differently.
At a time when competition is increasing in just about every sector, customers gravitate towards companies they like and avoid those they do not. And the decision to like or dislike an organisation is subjective - probably having less to do with products, services or prices and more with the people they encounter. In other words, customers may like a supermarket until they get to the checkout, where an unhelpful cashier can ruin the whole experience. Create a situation where enough customers do not like you and you die, he says.
So how do you make customers like you? Curiously, given the preponderance of loyalty cards, not necessarily by giving things away. Rather, the key is to add "emotional value" to the relationship, and essentially this means making some sort of connection between the employee and the customer so that the latter feels unique rather than a stereotype.
If that sounds obvious, Dr Freemantle makes no apologies. Lots of things in life are obvious, he says, but that does not mean people pay attention to them. The challenge of customer service, he adds, is applying the obvious to business.