At first I want to say, that I understand, that there are other more important candidates for future civilisation as Aztecs, Byzantines, Spanish or Japanese with samurais or other and Bohemia was not a major player on the field of medieval history like Mongols or France,
And there is Bohemian civ and campaign with theme of Hussites Wars in AoE 2 already,
But there is 1 single and proper reason - is the AoE 4 game mechanics would allow the potential of Hussites army / units / Hussites Wagons compare to AoE 2
Again this is subjective There is plenty of ■■■■ that went down in Bohemia that had huge effects around Europe. It certainly is more important than Spain in my opinion.
Please research more of the history. We want a Bohemian civ, not a hussites civ. There is much more ideas for a good bohemia civ that don’t make it Hussite focused (although this will be a big part of the late game).
Speaking of the wagons, it is sad that Rus’ are missing their mobile wood walls as well
Anyway, the point is, that Korean War wagon in AoE2 and German War Wagon in AoE3 work like slow , armored cavalry archer, this is not how the husites wagons worked, it was more like mobile fortification
BTW Hussite Wagons for HRE is nonsense for me, they were rebels against catholic HRE
AoE4 with unit abilities would allow to properly represent this.
And about the Bohemians - from my view , the hussites wars and warfare is what make Bohemian special within Medieval history.
Without Hussites, Bohemia would be one of many European medieval states / part of HRE as Schweinchenbab stated, and there would not be reason to implement them as own civ