Look in the last packs almost every time people talk about missing animals and what should've been in the pack, there is almost always mention of a bird, and a pretty popular one at that. With the barnyard, duck was missing, Eurasia - a pheasant or monal, from the Oceania pack budgies, Arid - Secretary bird, Tropical - any tropical bird in general, Grasslands Secretary again, Wetlands - pelican, swan or duck, and so on. So if these species were all requested at some point in time, why wouldn't it make sense to make a pack giving them all out at once?
Yes I agree that anything like a primate pack or whatever kind of specific group pack would not be for everyone, and yes it could end up the same way for a birds pack, BUT isn't that the case for any of the packs? There will always be a portion of the audience that doesn't like the pack, frontiers goal every time is to make that portion as small as possible so the majority will want to get the pack. A birds pack while not including free flying birds, would still round up a lot of species that people have wanted in previous packs all the way back to 2020 not getting stuff like the emu in Australia, which even though we got some of these requests later on, it still shows that people really wanted them.
I think as time goes on pack by pack, especially with packs that had habitat birds, people slowly start to accept that maybe we won't get a free flying birds pack, but they still want more birds in general even on land. Now that they have waited so long for people to start to accept this, the backlash for a ground birds animal pack wouldn't be anywhere near as bad as barnyard or other contraversial packs, assuming its not the last pack - but even if it is, would it be that bad?
Ground birds are very unique and diverse too, most are interchangable in size, behavior, colour, location, and a lot are requested. I don't see them all as 1 group because they are so different from eachother. For example, we could get the Secretary Bird, Ground Hornbill and the Greater Rhea in the same pack, and all 3 would be way different from eachother with 1 being from SA and the other 2 being different sizes and liking different living quarters. Secretaries like to live in solitary while Hornbills can be combined with several other animals.