Originally Posted by
bioblot
It seems people make use of semi-flex fares on routes where there is more than one flight a day. However that doesn't answer the question as to why BA sell these tickets on routes with only one flight where they offer nothing over cheaper tickets.
I suppose the answer is a mixture of "because people buy them" and "because not doing so is more hassle than it's worth due to our IT systems".
Because they do give you some degree of flexibility. There won't necessarily always be a fare difference if one can change for free and avoid the change penalty it may be a good deal for some.