I don't think EY have taken many new deliveries of 787s yet and they certainly don't have any A350s yet therefore I believe the aircraft shortage is still the reason why numerous routes have had frequency reductions.
I think QR will remain at one daily for some time but the variances in the departure times on various days is a good way of maximising connections.
EY and QR have far more to compete with at EDI than EK does at GLA for instance so we really shouldn't be expecting 100% loads all the time. These loads particularly on an efficient 787 along with the decent levels of cargo being carried are not a disaster by any means IMHO. But others may disagree.