Bank of America - What's Their Business Model?

We just don't get it. Big banks are in a terrible state right know and two things they need are money and good customers. We keep hearing horror stories about their treating good customers like deadbeats. Two weeks ago we received a letter saying our credit card rate would be raised from 10.99% to 24,99% and if we didn't want that to happen we could stop using the card. Recognize we had the card for years, used it regularly, were never late making payments and did not exceed our limit. By all measures perfect cutomers. Not being able to come up with any good reason to continue our relationship with Bank of America we called them, cancelled the card and smiled as we watched it travel through the paper shredder.