Why didn't TW just stick to the Warband system, this thing is all over the place?
Let's unpack that actually. The Warband system wasn't perfect, and it's actually more similar to bannerlord than you might think. Let's lay out the two systems, talk about their problems, compare, and see what tweaks we can make. Let's set aside how hard it would be to change the code for another discussion. I suspect that it would be trivial for what I propose at the end.
Systems Compared
In M&B, Warband, WF&S, and Viking Conquest, weapon proficiency skills increased with using the weapon and dealing damage. Everything else was increased by levelling up through experience gained per quest or defeated enemy. In every title but Viking, characters got one skill and one attribute point per level, and bonus weapons proficiency points. Viking Conquest was almost the same except characters gained two skill points per level and one attribute per five levels.
In Bannerlord, every skill has skill focus, and skill proficiency points. Proficiency points and XP are tied together. You gain one attribute every three levels, and one skill focus point per level. You level through gaining experience every time you increase a skill proficiency through using that skill. Every 10 points of proficiency, you gain a perk which is a bonus feature for your character, letting you do a new thing, or increasing your statistics in specific gameplay areas. Attributes no longer cap skill points. Instead both are tied to learning skill proficiencies.
In both systems, levels require increasing amounts of XP. There is no cap, but a character will eventually plateau. Skill proficiencies have a learning limit in both systems where progression slows to a crawl if you don't increase your attributes in the skill.
Warband's Problems
The flaw with warband was not in the progression loop, but that certain skills were incentivized over others to optimize a character. For example, leadership in Warband was not something companions could use to contribute to your party, so it was always optimal to level leadership, and let your companions specialize in the other skills. There were fixed companions with fixed specialties to make this a feature. However at high levels you could sometimes put skill points in to other categories if you maxed out what you wanted, and books could be purchased to level skills further if your intelligence was high enough.
Bottlenecks in progression were that some equipment needed a high skill, attribute. Armor needed strength, books needed intelligence, and ranged weapons needed their respective power skill. However, if you were bad in one category, you were probably good in another. Skills were capped to 1/3 of their attribute, so attribute allocation was the most important.
Warband's Problems
In Bannerlord a bottleneck in one category now can bottleneck your whole progression. If you reach high levels, you have to gain so many skill points to get a new level, you'll never be able to get the focus points to break past your learning limit. This means if you power level through focusing on one skill, you may not be able to optimize your character. There is no book system, and no bonus skill points per level.
In terms of previous titles is most comparable to M&B Viking conquest, but Viking conquest characters started with higher stats than warband characters. They also got two skill points AND bonus weapon proficiency points, so even in the slowest original game title, every level could be a power spike. This is not the case in Bannerlord. In Bannerlord, you are capped to five focus points per skill.
Comparison and Conclusion
Attribute points and increasing experience requirements slow progression in both systems. Bannerlord's current system doesn't give players enough of a power increase per level. Ways to fix this without switching to the old system would be to give attributes more often, start players with more attributes, or both.
We also haven't seen all the perk trees be reworked and implemented yet, and that could drastically impact how progression feels. If every tree has good low level perks, people might not feel the need to reach higher levels in as many skills.
Comments? Thoughts? Rebuttals?