Banks have to invest in mobile technology in order to keep up with millennials. But bankers also need opportunities to rub shoulders with young customers — and small, conveniently-situated branches give them an opportunity to do so.

Financial institutions need to have good digital offerings, but they also need to find ways to stand out from the crowd. That's why branches will remain a crucial home base.

Most customers who go into bank branches aren't in the mood to entertain a forceful sales pitch. But if they're pleased with the service they receive, they'll be a lot more willing to learn more about a bank's additional offerings.

Some institutions strongly oppose personalized marketing efforts, which causes branch teams to live in fear of breaking marketing rules and become complacent with the status quo.

This "product" is weakened in the customer's mind when interacting with a living, breathing banker inevitably involves fending off sales pitches, writes one retail banking program consultant.