Sure you could have some fun with it, but no longer than 2 hours maybe. It surely wasn't the ability to choose different builds that kept thousands of people playing warband for so many years. It was the clan-wars, duels, the competition, which is only possible with a stable combat system.
It wasn't any one thing. The ability for me to jump onto a server and play around with unusual and meme loadouts, probably lead to me getting hundreds of hours of playtime, when otherwise I would've thought that I can't be bothered because I couldn't pick some different and funny ways to pass the time with the game. I can only speak for myself(but I can reasonably derive meaning from the anti-premade avalanche on this forum), but the simple ability to choose gear was a signficant part of the formula for enjoyable casual play. I won't say it was the single monolithic thing that kept lots of people playing, it was a mix of mechanics and system designs. But the equipment selection system absolutely was a significant part of that 'blend', for lack of a better word. That almost all of the most popular multiplayer mods for Warband massively increased player agency in equipment selection points to it being a significant part of the formula as well.
The lack of equipment selection probably would've had a cascading effect. In Warband, as an example: I wouldn't have been interested in experimenting with different builds due to their complete absence, leading to me having a poorer understanding of the game. Combined with my inability to just join a random pub server and pick some weird loadout for the fun of it, and in turn spending all of those extra hundreds of hours practicing while messing around(most of which was in the beginning before I got good at the game); I wouldn't have developed the understanding of the game, nor the ingrained instincts of how to play it. I wouldn't have met other people doing the same, and developed ingame friendships and connections. So I wouldn't have joined a clan, nor become a competitive player in my region. Which in turn meant I wouldn't have spent hundreds of hours in scrims, practicing for scrims, official matches, etc. etc. I would've spent maybe a couple of hundred hours(at most) in Warband as opposed to 4-5k hours + developed a passion for the franchise. Without that passion, I wouldn't even be here in the first place, spending hundreds of hours reading over posts, reporting bugs, debating mechanics with people, and we wouldn't be having this conversation.
All of that, while partly speculative, wouldn't have happened if Warband had premade classes.
Equipment selection is significant to the formula of my personal Warband enjoyment. You might be different. Fair enough. But considering the mass outcry against this system, I can say with reasonable certainty that the majority of people around here probably have some kind of experience closer to mine, and consider equipment selection important to the Mount & Blade formula.
