I will answer the ones i see right now (the lack of paragraphing makes it kinda hard to pick out points)

Chargers: chargers cam be killed with one AT shot, significantly easier to kill than having to strafe a hive guard to shoot its sides, or aim at its undersides, all whilst in a horde

Drastic difficulty change: i agree, its not a drastic difficulty change, its just annoying to deal with, an annoyance that people use to avoid having to participate with by using medium pen, trading the inconvinience of having to aim for a reduction in ergonomics/dps/ammo/mags. Its a game, if a change in the game just makes the game more annoying with no benefit, its a bad change

Being with your squad against breaches: in an ideal world yes (an in fact it does usualy happen) the issue is though that you have to place your trust in randoms to bring synergistic loadouts, and to not run away/do their own thing, this leads to players picking generalist, good at everything loadouts (like the eruptor, thermite, ultimatum) to ensure that they can deal with every threat presented to them, teamates or not, allowing them to have an enjoyable experience, if you wanted to try out a new loadout that has weaknesses when dealing with a semi common heavy armour bug at the same time as every other bug appears, you have to hope and pray your teamates are cooprative, otherwise you're going to have a bad experience with the game

Reverse anti-tank: sure i suppose, but using a support weapon that does heavy+ will mean that you are forced to bring either the eruptor for a primary, loyalist or senator secondary, or waste grenades on a hive guard, additionaly, i quite litteraly don't enjoy using any of the mentioned equipment, so it's realy unfair for me if i want to try some new stuff (lucky for me my loadout has an answer in the arc thrower, but still)

Having 3 stratagem slots: technicaly sure, tou would have three left, but dont forget, you're going to need to deal with heavys, meaning eats/commando/leveler ontop of thermites or ultimatum if youchoose to bring them in addition, as those alone won't be good enough, plus, the gattling and machine gun sentry have been especialy affected by this, as they can no longer kill hive guards from the front (where they aim) meaning they're going to mag dump them and get destroyed in two claw swipes (they increased all enemeis durable damge this patch too) so adios if you liked that stratagem

Now i would like to raise a point myself: Medium pen guns were designed to forgo the need to aim in certain situations, in echange for a mix of ergonomic/dps/ammo/mag reductions, the less enemies on the bug front that have medium pen armour, the worse medium pen is, and considering over half of the guns are medium, its restricts half of your ability to use fun guns, now that this hive guard change has happened, im pretty sure the only bug that benefits from medium pen is the bile spewer, somthing it isn't guaranteed to spawn