While I tend to get mad at the cafe dwellers that spend 4 hours on a table sipping on the same latte, I disagree with you here. It's all about finding the middle ground. I have had to work in coffee shops before and if you hold yourself to a code of conduct (e.g. consume something regularly, don't take up too much space, pack up and move somewhere else when it gets busy and you see people looking for tables) you are literally costing nothing to the coffee shop, while making it appear more full.

The problem isn't laptops, it's people being assholes.