While that should be considered I also think there has never really been the right sort of airline trying them, ironically enough its a carrier like Flybe who would be ideal for BOH, maybe with a smaller ATR42 sized a/c. I agree BOH has never done so well with the routes but many attempts have been ruined due to bad timing or size of aircraft (FR to EDI/PIK, BE to MAN, WW to JER). I doubt BOH would ever be able to sustain more than a couple of routes, and certainly never an operation like Flybe's up the road. However I don't think its impossible for it to sustain any business routes, however it is not easy it seems to find the ideal Airline/Aircraft/Frequency combination so in that respect BOH does struggle.
However I completely agree the primary cause of any growth at BOH would be through Leisure routes and also non-passenger activities.