I suspect there is a lot more to installing rear facing seats than turning front facing ones round.
With rear facing seats the crash loads exerted on the aircraft by the passenger’s inertia are greater and more complicated. On impact a forward facing passenger merely stresses the seat through the lap strap attachment points which are quite low and produce limited tendencies for the seat to rotate top forward. Once you turn the seat round the passenger is supported in the sitting position and you have to consider where the passenger’s cg is. If this is only inches higher than the seat belt attachment height then there will be much larger seat rotating loads to be taken out by the floor to say nothing about the extra strength needed in the seat back itself to stop that breaking off backwards.
So sadly rearward facing seats have to be stronger and so does the floor. This either means more weight (more of the same material) or more cost (changing to stronger materials) or a combination.
Mind you I believe such extra safety (and its costs) should be mandated through airworthiness requirements and the ticket price adjusted to whatever it needs to be as a result. The same as the provision of sensible comfort levels by higher seat pitch minima. But there you go, old reactionary farts always say things like that.