And having more fire buttons help that?
Yes, it very much does. I take it you don't fly a Corvette or Anaconda in combat regularly or else you wouldn't be asking this question.
My Corvette has two efficient beams as my primary weapons, plus a large corrosive MC, a pair of medium corrosive MC turrets and two missile pods. There are many situations where I want three or more fire buttons (plus a turret on/off toggle) to manage these weapons efficiently.
I use my beams as primary weapons, and due to cap draw I want to fire my beams independently against shields. That's fire button 1.
I use my large corrosive MC against larger ships, but only when shields are down, and I will often want to fire the MC independently from my beams. That's fire button 2.
I use my MC turrets against smaller ships (to conserve ammo) but need to toggle these on/off when they fire chaff. That's an entire fire group because I can't toggle on/off with the fire button, I have to deselect the weapons entirely. That would be fire button 3 if I had it available.
Against a smaller target trying to escape, I'll use missiles, so I want these separate and immediately available. That would be fire button 4.
At present I only have two fire buttons and two fire groups and I have no way to use the missiles effectively with that setup. I can't use more than two fire groups because I use the groups to quickly toggle turrets on/off and three groups is just not efficient for that purpose. If I dedicate the second fire group to missiles instead of turrets then I can use missiles but I can't turn the turrets off and that wastes ammo. It's a clumsy setup where I have to choose between having an efficient turret toggle (i.e., second fire group to turn turrets off quickly) or efficient access to missiles (which I can't put on any other fire button).
If I had three fire buttons and a turret on/off toggle feature (which should already be implemented) my problems would be solved. I could just switch fire groups to make missiles available since I wouldn't have to dedicate a second fire group for turrets. At the moment my Corvette's weapons are not being used most effectively because of FD's unnecessary limitation on only two fire buttons and no turret toggle, which is quite simply a terrible control setup in any game, especially a professionally developed AAA game.
Needing separate buttons for SCBs (which my Corvette and other medium/large ships use regularly) and chaff (which all of my smaller ships carry) makes the fire button limitations even worse. It's not just an issue on larger ships, even smaller ships with two different weapons plus chaff and SCBs run into problems with the limited fire buttons and keybind options. On my Vulture for example I have a dual chaff setup (which I can toggle using a fire group) but I also need to use a heat sink prior to using an SCB due to the heat damage so I really need to dedicate two buttons just to use a SCB properly. If we could bind more than one function simultaneously to the same button I could fire an SCB and heat sink simultaneously with a single button press but FD's keybinds aren't sophisticated enough to be customized in this manner, and even if they were I would need to reset my keybinds to do this every time I switched out from my Vulture to another ship (since I only need this option in the Vulture as a result of the poor heat management combined with a powerful class 5 SCB in its military slot).
Again, maybe if you flew large combat ships with four different weapons and wanted a turret on/off toggle, you would.
All more fire buttons will allow you to do is have instant access to different fire groups....so by making it more complicated to remember what fire group you want to utilise and what fire button it is mapped to. So really a slight variation on the current setup.
No, more fire buttons would allow me to utilize my four different weapons effectively in different situations. If FD would stop designing large ships with four different sizes of hardpoints we might be able to manage with only two fire buttons, but even then it would still be inefficient.
Again I can why some people would 'want' this but that makes far from a 'need' or 'must have' by a long stretch.
It's a "need" in the same way that other critical flaws in the game need to be improved if they want to remain competitive in the space sim gaming market. At present the only reason they have gotten away with the game's control setup being so inefficient and frustrating is because there are no other competing games on the market right now. If they had any real competition then they would absolutely need to make these types of improvements. The worst part here is that the devs apparently don't understand their own game and claim that the lack of fire buttons is a "challenge" rather than understanding how terrible their current control setup is. Given how many of their players (myself included) grew up playing flight sims that type of explanation is not only ridiculous and condescending, it also causes a profound loss of faith in the ability of the devs to develop and improve the game's core gameplay.