Here's some other (bad) reasoning as to why the class system was included:
1)
"Bannerlord's main Multiplayer modes were designed to be dynamic and intense, and one important goal was to have fluid roles so that players could quickly switch between roles to try a different game plan or to counter their opponent's tactics. This is best achieved with a class based system. With the current system, if you want to switch from an archer to a knight, you can do it in a split second as it takes only one or two clicks. With an equipment system, you would probably need to select a horse, lance and shield at a minimum, and then to armor up, you would be picking a higher tier helmet, pauldrons, a hauberk, gloves and boots. That is too many clicks and would ruin the kind of fast paced, intense and meaningful decision making we would like the player to engage in."
To spawn in as cavalry in Warband, you only need to select "cavalry" and "done", and then you're there as cavalry. You don't need to select a lance, it's already selected by default. (It's honestly frightening if TW doesn't understand this about their own game.) The default loadout for cavalry is closer to the optimal 1000 gold build than the other classes, so it wasn't the best example to illustrate the point. With 1000 gold, selecting a Hunter horse might be the only really significant change to make from the loadout, it's still not necessary (you get a Saddle horse by default), and it's just one change.
Imagine if you were telling your teammate during a match to spawn in quickly, and they were saying: "I can't select the gloves in time! I won't be able to make it!" Just leave the gloves. It's not important.
Something like the "quick selection" in Bannerlord's class system could be achieved through Warband's item selection anyway. You could've had a suggested loadout (i.e. using up the 1000 default gold). Or more than one suggested loadout per class. More expensive suggested loadouts could be made available only if you have enough gold. It would be like applying Bannerlord's style of selection on top of Warband's without destroying it. This would allow you to spawn in quickly with a decent build, but you'd have options to customise if you want.
In all of the streams I've watched of Skirmish so far, I've never felt excited about any "change up" of tactics when players respawn as different troop types in the middle of a round anyway. If that's what the inclusion of the class system is mainly about, it's not a good trade-off by any means. Battle mode's positional element in tactical play was so much more interesting and engaging. It's something that really distinguished the mode, whereas Skirmish's multiple spawning just makes it feel more like TDM. The fact that you can kill a player and they might return seconds later makes getting kills less satisfying too.
At the same time, Captains fails to deliver on the positional element in tactical play, because the poor functionality of the AI reduces the tactical possibilities. They can't even climb ladders properly, which I'm guessing is why ladders aren't included in the mode at all. The large blobs of AI will never be able to do as much as what real players could do. It doesn't owe towards the kind of depth and interesting gameplay that's unique to M&B with its style of combat.
2)
"there are only so many different combinations of items people use which results in the class system not being any different practically. M. Arda continues in support of this, saying that in the case of there, for instance, being five different choices for a sword with them differing from one another by a damage difference of 2 and only two of these swords being the popular choices results in rendering the remaining three useless (He's basically trying to say that there is no point in having multiple variants of an item that are nearly identical to each other). He calls balancing Warband's system a "pain in the ass" and the current one easier and faster to develop which is immediately contradicted by Gökçen who points out that balancing the class system is far more time consuming to balance and refine. Gökçen continues saying that in the long run the class system will be more beneficial in regards to balance and that even currently, it is more balanced and the only imbalance there exists is that certain factions are used more often"
No one is requesting the inclusion of five almost-identical swords again (if that even is the case, I remember some tournament duelists opting to choose the short swords for Swadia). Make the choices more meaningful or include fewer choices in the same system if it's really so problematic. It's no justification for all of what Bannerlord's class system entails.
It's a shame if they can't be bothered to put the work in (calling it a "pain"), but they have an invaluable resource (i.e. their community) to help them work on the MP and balance it out. Bannerlord was a chance to genuinely improve on Warband. Or at least deliver something different in the same vein. A new arrangement of weaponry in the traditional item selection with new factions would've been something to look forward to. Instead we have something that isn't in keeping with M&B's spirit of sandbox and customisation at all.
One reason the class system is different is that it doesn't provide the "middle infantry" as consistently as you were apparently choosing it in Warband. With the default 1000 gold, you could always afford a basic-but-decent setup (e.g. free 1h sword, strong shield, short awlpike, middle helmet, middle armour, gloves). But with Bannerlord's class system, the forced minimum is a prebuilt peasant troop with either a shield or a spear, a floppy elf hat and baggy trousers. You have to wait to play near enough the equivalent of what you played by default in Warband.
It felt great upgrading to an awlpike as Vaegir infantry (which you can't afford with a decent build by default), but in Bannerlord the upgrade you get in terms of a polearm is to get one at all (unless you don't want to protect yourself from archers with a shield). That's not fun, that's just annoying. You can't always find what you want by looting either, and it'll be gone again when you die.
In Warband's Deathmatch, you could select the best of every item type, and the game would automatically upgrade for you as you get kills, if you want. The changes were more gradual, and it mostly stayed in the style you would choose. In Bannerlord, it constantly switches you between different prebuilt troops, with items you don't necessarily prefer to use.
Managing the class system across all the modes (not just Captains) is another issue altogether. Especially if it's setup to be tactical, some of what might work well for Skirmish (i.e. with precise teamplay and communication in mind) might be annoying in TDM or Siege, where there's more chaos and less cohesion going on.
Having said all this, the class system doesn't matter to me as much as the general mechanics. I'd even put up with the crashes and sound bugs if I found the "feel" of the game to be more fun.