I agree with most of the OP.
Odyssey feels like it was made by people with no experience in making FPS, and very limited experience playing them. Which is likely true, after all. There are many "golden rules of FPS" that are basically ignored, and they slapped their own homebrewed stuff because obviously Fdev can do better than companies that have made FPS for decades.
Reinventing the wheel is usually a bad idea. Especially when your company is not known for making FPS games (did they make any ?), and as such, is lacking experience.
-the kin/laser-shield/health mechanic is completely bad. This is further emphasized by plasma weapon, which ignore the mechanic. The only way to balance that is to either nerf plasma to uselessness (currently the plasma AR), or let them dominate (the other plasma weapons). It works in space because we have always more than 1 weapon, so we can have half-half. In ground, it involves constantly switching, which is weird and clunky.
-pistols in FPS are sidearms. They support your main loadout. The golden rule is "switching to your sidearm is faster than reloading", and has been true for decades. It's also intended to offset your primary weakness (short range sidearm for a sniper rifle user, or the opposite for a shotgun/SMG player)
-FPS is all about awarding skills. Mostly through headshot (or weak point). Odyssey doesn't reward that when shield are up. There are no HS on shield. This need to go.
-No combined arm, and no combined arm mission. The CZ have ships and turret, but they are separate from the ground combat. Ship are super OP against ground troop, unless the ground troop have support from turrets, in this case they are super OP
-due to the aforementioned laser vs kin choice, weapons are not defined by what they are (IE sniper rifle is a sniper rifle), but what type of damage they do, since we don't have all the category for each type of damage. For example, there is only one sniper rifle and one shotgun.
-sniper rifles are not sniper rifles. In FPS, a sniper rifle is a pinpoint accurate gun with big burst damage. The biggest high skill-high reward gun of the spectrum. In Odyssey, the projectiles takes up to 2s to reach target, and is not pinpoint accurate (unless modded I think). Making it more a medium range weapon
How it would work :
-balance the 3damage types differently. Laser is hitscan but less damage. Kinetic is high damage but affected by gravity and slower. Plasma is even slower, but with a small AoE radius and highest damage. OFC this would need balancing around, but you get the idea.
-make sure each damage type has appropriate weapon type. Shotgun/pistol/AR/SMG for all, sniper would need some work (kinetic is a regular "big boom", but perhaps a DMR style rapid fire one for laser, and perhaps none for plasma ?).
-balance weapon around the damage property so they aren't useless compared to another. So, a laser shotgun would have less falloff, kinetic shoot faster/more ammo, plasma is lethal but limited ammos (kinda like now).
-headshot and weak point need to be rewarded at all time. High skill -> high reward.
-make melee MUCH stronger. In FPS, melee is highly rewarded because it's difficult to get into melee range in a shooter. Once again, high skill->high reward. In Odyssey, it does so little damage, it's best to keep shooting.
Then you'd need to tackle the combined arms aspect and so on, but that's be a start IMO.
OFC, that will never happen, but whatever.