To be fair, frequent schedules ex LGW to many of Europes major Cities make EZY quite a popular choice for business passengers. What you have to remember is that businessmen aren't always execs and they aren't always suited and booted. Lots of technical staff, shop floor personnel etc etc travel on business.
There is also a gross stereotype of the business passenger. From experience they are generally easy to please. Most aren't pre-madonnas, they generally get on, sit down and don't give you any trouble. Generally polite aswell. As much as I like holiday flights, the city routes are actually quite easy for crew.
As for the terminals themselves, some people like to nicely box certain airlines into certain terminals. In essence that doesn't tend to achieve anything. It's no good grouping airlines together if one terminal becomes dead late afternoon whilst the other is having capacity issues.
Specifically easyjet, I think the operation at LGW might just be too big for just one terminal.