for those unaware, hive memory was a often talked about and finally test implemented system where xenos that die as an upgraded form can respawn as a slightly less upgraded xeno, or AS A T3 XENO, CAN RESPAWN AS T2 WITH THE ONLY PENALTY BEING A SMALL PART OF YOUR EFFORT BEING LOST
first of all, and most importantly in my opinion: it removes the sting of death, and rewards dying players. The entire point predicated on CM's xenos is that they are powerful fighters that slowly get stronger as they live, culminating in xenos that can singlehandedly fuck shit up, the counter balance to this is having your entire progress erased and having to start from scratch keeping every xeno in check, making death matter, making it important to prioritise survival over frags (which fits pretty well within the concept of the xenomorph and hive). With hive memory, it does erase some of your progress, but not all of it, allowing death to not matter as much, as it delays your ability to play, and removes some of the time you spent getting to where you are (T2-T3 is really not as bad as it may seem, only a delay of usually 10-20 minutes at most). The tension of fighting a dangerous well armed foe, with the potential to die at any moment and lose up to two hours of progress in an instant is what gives playing xeno its edge, but with hive memory death isn't as much of a punishment, thus some of the stakes are lowered. I don't speak for everyone nor do I claim to, but I would bet that playing xeno would lose a large amount of appeal once players realize how meaningless becoming invested in staying alive and getting more powerful is when it can be pretty easily reclaimed. Where before death was a harsh slap, coming usually at the hands of dodgeable explosives or getting yourself caught in concentrated lanes of fire, now you are rewarded inadvertatly for dying with a small setback in comparison to the complete progress wipe there was before, which is in general a terrible design decision when there is semi perma death and you're supposed to care about your character.
For marines, killing high level xenos is supposed to be a huge thing, it cripples the hive, takes out one of their major resources, stopped a perfect killing machine, and in a minute of fighting wipes out up to 2 hours of someone waiting and slowly becoming stronger, it's a rush, and hunting T3s and killing them is one of the most rewarding experiences as a marine because you know how much of a difference they make on the battle field and how far you've set your enemy back by killing them, but with hive memory, an elder lurker can come back(with the same number, almost as if to taunt whoever killed them that it was pointless) as young and with a relatively short period of waiting, can get right back to where they were, meaning that the big high tier frags that might swing a fight around becomes dulled as you realize its still a set back but not nearly as much as it was before.
I'm not sure about the statistics of how it works within the hive tier system, but imagine someone joining the round as a xeno for the first time that round and trying to play their hand at a T2 or T3 but getting blocked because someone who failed by dying gets it before them, if tier spots are taken up or blocked due to hive memory, that would reduce the amount of chances players who haven't fucked up get to play as a higher caste because the player that has already had the chance to be an ultra urist mc robust died and lost it still got in due to hive memory, imagine how salty that would make the other player if they knew that they can't become T2 because the dumb young rav suicide charged the enemy and just respawned as a lurker to do it again.
Honestly, I think I'd be fine if hive memory was restricted to T1 maturity level, because it wouldn't actively fuck with anyone else in the hive's ability to play the fun castes, but it would not be too big of a reward for dying to be worth caring about for most people.
Sorry for the shit grammar, let me know what you think about the hive memory change and let me know if I got some part of it wrong and misunderstood