There is a point here, the optimum platform may not be a big jet which tries to do everything. A platform which can be re-rolled quickly to be able to do the high impact but infrequent missions will be cheaper. Why carry an acoustic system, launchers sonobuoys etc on a maritime surveillance mission. If you stumble across a submarine you will be able to track it until it goes sinker. In peace time that should be enough. Remember we are now intelligence led! If there was a chance of stumbling across something the ac fit may be different.
Not only a very valid point, but in point of fact, everybody posting here that flew on the rod has already been there. We have flown countless times with missing, broken or semi broken acoustics and/or diminished/absent sonobuoy loads on sorties where ASW was not on the agenda. During Op Tapestry (got to be my age to remember that, fishery surveillance for the youfs amongst you ) we often flew with only one wettie and he did radio (yep, wetties usd to do that on the mark 1).
I'm not saying this is a viable option...I'm merely saying it's a valid point.