Racedo, I am certainly unqualified to comment on any strategic justification although, to an untrained eye Saint Helena doesn't seem to be a great deal closer to a certain group of islands than is Ascension and, at the same time, it does seem to be even further away from such as the UK and Gib.
I suspect that income from tourism might increase substantially and consequent employment may well allow allow reductions in the substantial (per cap.) and gradually increasing UK contribution to the island's economy. There will also be direct income from the flights and supply of related services too. Perhaps, these days, better provision is due for medical and other services for the population, especially if we are keen to keep criticising others for their attitude to human rights...
I wonder how their income from postage stamps is holding up in this digital age. There no longer seems to be much of a market for anything else that they can produce.