As has been amply repeated in this thread, the specifics of the Flexi Season have the imprints of both DfT and Treasury all over them. The (unsurprising) biggest disappointment (or expectation) for many is that there are certainly not universal big savings, but they will offer some savings to some travellers on many flows. The big issue for Treasury is that until there is a proper post lockdown return to work, the degree of (semi) permanent loss of commuting traffic is unknown and they are terrified of accidentally giving too much away in terms of discount.
The other elephant in the room is that all the while the Season Ticket, the daily fares and the relationship between the two remain unreconstructed there is desperately little room to squeeze in a new fare. Put simply, daily peak fares are quite expensive but Seasons, although perceived of as expensive, generally offer pretty good per-day travel rates on the basis that the customer has paid upfront for unlimited travel. This is quite a significant white-collar subsidy that goes not to the lowest paid in general (cleaners, part time workers etc) but to better off people in reasonably paid jobs. Over time, as people's travel patterns post-Covid become established, it is probably going to be necessary to redirect this so that the benefit is less tilted towards the season ticket and there is a more even spread between full time, part time and daily travel. The kind of experience in working this out won't come from arguments between Treasury and DfT.
However, the other aspects (child fares, missing flows, 1st class) can all be picked up in due course - what's there now isn't what has to be there for evermore; and of course as at long last a national strategic approach (rather than a TOC approach) to ticketing can be established, the delivery mechanism should be able to become more consistent across the network - for now, the developers had to work with what was there.