Main switches are a bad idea. It's dangerous in that anyone can flip the switch by accident and cause your plane to turn into a raving wolverine in the pits. It's expensive in that it's not only extra cost, but a moment of forgetfulness will cost you a battery because the ESC is always draining energy any time the battery is connected. It's an extra point of complication. It's an extra point of failure. It's extra weight; we're not talking about a little toggle switch here.

There are too many disadvantages and not enough advantages. I would highly recommend that you seek out some of the techniques people have shared on loosening up Dean's Ultra connectors to make them easier to connect. Personally, I will plug a male end into a female and give the male end a good bit of torture with the soldering iron to loosen up the fit.