Why can't we have five classes?

I'm curious as to why we always seem to be stuck with only four classes in battlefield titles of late. From a balance perspective it comes across as an odd choice as there's always one hybrid class per title that is what i'd call a slightly too strong to a clearly overpowered, eg.

Assault / Medic in BF3 / 4.

Support / Engineer in BF1 / 5. 

Support / Medic in BF2042 / 6. Which are by far the worst offenders with open weapons being included.  

I know with supports supply pouch the intention was for it to be a super helpful, clear and simple " does it all " gadget and it is. But it is too helpful, to the point that it can be used in a selfish manner. Nothing promotes selfishness like a gadget than does everything for you, it makes you a self sustaining army, no need to interact with anyone as i have all i need right here.  

Recon and Engineer are both decently helpful and bring their fair share to the team. 

Annnnd then we have Assault.. With a ladder and an EpiPen that makes your vision blurry...

So to combat this i suggest the supply pouch gets split up into three,

Medic gets a health bag - Being medics... 

Support gets an ammo bag - LMG go BRRRT and needs feeding...

Assault gets an explosives crate - Since they primarily have infantry focused explosives. 

They all contribute to the team and have something that complements their own playstyle/ weapons/ other gadgets without being totally self sufficient. 

Now, i know what your thinking " That'll just lead to grenade spam from Assault players " to a limited extent you're correct, but it'll also stop Support players with infinite mortar shells camping in spawn.... Don't forget, without a Support player nearby they'll eventually run out rounds with their primary which is a far, far more effective weapon. So it is fairly balanced in that regard. 

Also, five classes with the squad count remining at four would keep things interesting as no squad would be able to have a " fully effective team " as it were, a skillset of some kind would have to be dropped. 

This is a rough lineup with current and made-up gadgets. Obviously other gadgets may need to be shuffled about or rebalanced but its a start. 

Assault - Loses Deploy beacon.  Gains Explosives resupplying crate.

Engineer - Unchanged.

Support - Looses Supply pouch, Defibs, Smoke grenade launcher.  Gains C4, Ammunition bag.

Recon - Gains Deploy Beacon.

Medic - Gains defibs, Smoke grenade launcher, health bag, Flashbang airburst, deployable cover, claymore. Carbines as the class weapon is probably the most appropriate.

No one is useless, no one is overpowered, most importantly everyone does something useful. 

Thankyou for reading.