Here at waterside BA Headquaters most people may have knowledge of Kent but I doubt the majority have ever heard of KIA. STN is geared up for our flts and many other wide bodied frieght a/c. Futhermore it provides a centre for the SE UK with ease of access to the major motorways. It is also important to consider how the customer views the operation, STN is a major UK airport instantly recognisable. To start an operation at KIA may lack customer appeal and moving out of STN immediately lets someone else move in and take your business.
In this climate be thankfull for the little bit you have got as things can only get much worse I fear. Finally both LGW and STN have lots of capacity at this time, no doubt both will be actively seeking new customers and undercut anyone when the need is great.