It is widely acknowledged that currently, all sorts of knights and horse archers just kind of dominate this game, while barracks and melee infantries being somewhat dispensable. This cav meta has been controversial for a rather long time, and there are already plenty of discussions on improvement, like nerf the knights or buff the spearman.
Here, from a new perspective, I think maybe calvary meta is actually reasonable for this historical game, as an elite calvary army can always be a dominant force historically in the game’s background era. The real improvement should be about, what role should melee infantry take to fit in this meta?
In my opinion, as players will always need calvary as their core mobile forces and ranged infantry for their DPS, melee infantry could perhaps change its current awkward position into a supportive force. An initial idea, brought from camel/infantry support from Abbasid/Ayyubid and Kharash from GH, could be making them able to buff nearby Calvary, ranged units, siege engines, and maybe even workers and buildings, to have extra armor and hp (providing cover for friendlies). They might also be enabled to buff attack speed of keeps, outposts, and even siege engines (providing logistic support).
Another small idea just for fun is that perhaps every nearby melee infantry can be allowed to raid some resource from TC, landmark, houses, and maybe even resource drop off buildings? (when destroying them, an idea brought from Polutasvarf of Macedonian Dynasty) This in my opinion can make playing melee infantry much more interesting with this high rewards, while also reflecting the nasty truth of wars.