There are various reasons for certain flights being cut. Harare nonstop would entail crew overnighting in Harare which the unions would not allow, or the carriage of a double crew to tak ethe aircraft to a final destination such as Lusaka, Maputo, Durban, etc. Often the unions will impact the survivability of a route as once already mentioned in another thread Air France used to operate an old UTA route CDG (changed from ORY) to Luanda and then on to Gaborone. This was a combi 747 with 4 Flight deck and 27 Cabin crew to handle both sectors as the Air France union refused their crew to stay in Luanda even though there was a Meridien hotel in Luanda, so the crew would stay in Gaborone, for one week. I know this as the crew stayed in my hotel, great for me, but a costly route for AF. I no longer have that hotel, but it was a great time. We had the BA crew as well, but they only took 5 day rooms, 4 for Cabin Crew to share, and 1 for the flight deck to share as they operated a twice a week shuttle frm JNB to GBE, on the other days the aircraft (744) went from JNB to DUR or sat in JNB, with the BA crew having a base in JNB.
These kind of flights do cost a lot to operate when these extra type of costs are added in. As Sparky mentioned KLM has been flying to JRO for ages, but the crew stay in DAR due to lack of adequate accommodation in JRO. For BA, I think an in season route to Mombasa perhaps continuing on to Seychelles or Zanzibar would certainly suit the British leisure client, served from LGW on a three class 777, or perhaps with the new 787`s. Not sure of the traffic to JRO would make that a likely destination, but would be intersting as an add on as well. For me, Maputo is a great opportunity solely served by TAP or LAM so this could be a good addition, perhaps first with the BA subisidary Comair?