I doubt I'll have my travel plans for getting to the airport in order 90 days before and most travellers won't either - because most airline tickets are booked within 90 days of travel.
This, like other onerous advance purchase schemes, is mostly a marketing show and will have little applicability to the average passenger and little effect on revenues. Which I'm sure is the idea.
The HEX should cost about GBP10 each way maximum.