Call me cynical but LBA-LGW has failed before
Okay. You're cynical. Flybe seem to be making a habit of taking routes into LGW that others walked away from (ABZ and BA, NCL and Jet2 spring to mind). No reason why they shouldn't do the same with LBA.
it doesn't offer the connections that a LHR route does, I am not as enthusiastic or as hopeful as the above.
It (LGW) also doesn't involve a regular 20 minute hold, 15 minute taxi to stand or 20 minute walk to the tube before finally arriving in Paddington. One or two plus points over LHR even if there aren't the fabled connections LHR (sometimes) offers......