Perhaps in part it depends how easyJet view a particular route. AMS for example is obviously seen as both a business and leisure destination and the timings of flights from LTN for instance at the beginning & end of the day attract passengers on business or leisure trips.
Perhaps with a route such as MUC, its not seen primarily as a business route from LTN or STN hence the flight timings they have gone with?
You're right that the focus of easyJet's business is clearly around LGW and perhaps more could be done elsewhere. LTN does seem to be benefitting from more routes & frequencies. Hopefully as the airport expands, this will increase and maybe more flights and routes timed for business travellers will be the result. Time will tell.