The old business saying, "Nobody was ever fired for hiring IBM," should have this corollary-- "People got promoted for hiring IBM." Vendor choice and experience helps launch (and destroy) careers. I knew a young manager who became a young executive in a Global 500 bio-medical company, not long after ushering in a successful enterprise implementation. He deserved the promotion, but wouldn't have gotten it without the vendor's splendid performance.
My friend probably made sure this vendor's plan fit their business well. Studies and personal experience show that customers want their vendors to know their business better. By doing homework and aligning their products with the business challenges and goals of customers, vendors improve chances to win and/or grow account and market share. But what about learning the goals and issues of individual contacts at key accounts as well? If they influence choice of vendor, and that decision reflects on them and their careers, then it would serve the vendor to know these individuals better as well as their business.
I suggest that knowing your customer contacts better can parallel the learning of their business. For example, when conducting due diligence on a key account, best practices would identify the challenges faced by the business, strategies undertaken, and most critical business performance measures, so your product can be adapted to fit into that customer reality.
But some answers needed about your contacts are similar -- their career goals and challenges, what they have accomplished to date, how they may be affected by the degree of success in the vendor/partner relationship. The outcomes will guide building in features and assurances that accomplish the personal needs of your contact along with the business objectives. This might include a preferred frequency or mode of communicating project progress, or preparing the ROI story a certain way for the executive audience.
Customer contacts will tell you they want effective solutions from vendors rather than to be wined and dined. But creating some social situations can pay off if that is where we learn about the client as an individual beyond what can be obtained through social media.