So why don't we have rearward facing seats...
Good question.
The usual reply is "passengers won't like it." Passengers don't like lots of things, like security, but when there's no option they'll accept it. The real problem is spineless regulators who won't force the industry to introduce it.
I tried once, in the '70s, when I was in a position to make a change with a small fleet of 40-seat turboprops mainly flying charter work for a small number of clients (oil companies). We identified a suitable seat, rear-facing, 9G back, no recline, etc. No sector was more than 30-40 minutes. The additional weight of each pair, with the stronger back, was such that 19X2 seats weighed the same as 20X2 forward facing seats. The floor mountings were fine for each type of seat, as you would expect.
The idea was dismissed as dangerously fanciful by our clients' accountants, who regarded the loss of payload as totally unacceptable. "But, think of the added safety in a survivable impact," we said. "Get lost," they said, "who cares about that. Just make sure we get the sector payloads we're paying for."