well for starters, PvE doesnt need the upload decay timer, that's meant to keep people from hiding stolen goods without people being able to get it, a personal vault, while in PvE this just hurts players who either A) are not able to get cryopods yet or B) are trying to store unpoddable tames such as the stryder or titans, now, that being said a player should only be able to have 1 titan in upload, but the stryders are a big problem
next, quetzal are not obsolete, i use them quite often, the genisis 1 boss fight is probably the hardest fight of all of them (except maybe king titan, but even then king titan isnt really hard, just needs a lot of prep) yet gamma final test is too hard, from the gigas in the arena being able to bleed to the fact you HAVE to go on foot and survive the mob in order to even progress, quetzals only become obsolete after you beat that and even then, a good quetzal will easily surpace the skiffs weight and health, as well as if you want to store things on it you can put it on passive flee to have a better chance, quetzals are also breedable, so while a skiff is cheap, a quetzal is cheaper, and the only thing it loses is speed and the ability to pick up things larger than mammoths,