Two reasons.
1. The internet and immediate news was not so widespread...............
2. 340s hadn't already had a history of catching fire................
Maybe third and fourth reasons:
3. Too loud advertising campaign, manipulative name, self-applause. Very nice, good, promising and interesting plane but overweighted with unbalanced ovations, superlatives, glorifying....
4. Increased economy at the expense of safety...?
Sorry for o/t