A challenge here is that product innovations can irritate customers who invested in the last-generation product; think of Apple, which routinely ignores minor issues like backward compatibility among its products. Also, a focus on customer relationships means offering each customer-tailored services -- something that's tough to make coexist with operational excellence, which depends on perfecting repeating processes.
A related challenge is that operational excellence generally means defining what the company does and doesn't do. Operational excellence means explaining to customers that "This isn't how we do things," "It's against our policy," and "If we do this for you we have to do it for everyone." So it takes a backseat to customized service.
Operational excellence companies sell on price and quality. "Quality" in this context is defined as the absence of defects, as opposed to "excellence," which means the presence of cool features -- a hallmark of product innovation companies. If the distinction isn't clear, consider the Toyota Corolla -- a high-quality car -- and compare it to the Lamborghini. I can't speak to the current crop, but I recall the Countach, which had a reputation for leaking oil all over the pavement. It was an excellent but low-quality automobile.
Operational excellence companies generally pursue mass markets, as this strategy is a high-overhead-cost/low-unit-cost approach to doing business. This trade-off makes the most sense when what you need is for the marginal cost of making one more unit to be low. Mass markets don't exclude good customer service but generally leave out deep customer relationships (as I already mentioned).
You're right that these three aren't mutually exclusive. The challenge for each company is to determine how they want to balance the three, because they do involve trade-offs.