I know where you're coming from, but in my opinion infantry in M2TW has been portrayed in an underwhelming fashion!
First off - I understand that hardware requirements have gone up significantly, as has number of polygons per unit and it's beneficial for us to play with smaller unit sizes, but it has robbed the game of its cinematic feel.
It would take me a loooong time to inspect my, say, macedonian army on the field. 10 - 12 huge units of phalangites really made ground tremble and gave off a sense of serious clout when sprawled across half the map (esp with darth formations in XGM). Infantry armies in Rome were enormous!
Somehow, 8 units of Italian Militia, with the feeble patter of their tiny feet, doesn't really cut it for me.
Secondly - cavalry is particularly nasty in M2TW and will gut pretty much any infantry unit, usually head-on, occasionally even in thick woods. It is perhaps a fair illustration of improvents in armament and gear (stirrups!) which elevated cavalry to the top of the food chain on most medieval battlefields.
There are other reasons too - commanding infantry is generally easier to grasp and has fewer snags than commanding cavalry in M2TW, and as such i find it less tactically challenging and ultimately rewarding. This is just my personal take on the game so do not feel offended!
I actually know exactly what you mean and I second that in a way, infantry-biased battles in modded RTW were immense in scale and generally excellent fun (XGM, EB, RTR), but in some TW incarnations (STW and M2TW) commanding cavalry is just more fun for people like me.
As Empire TW is coming out you should keep banging on CA doors to give infantry justice this time round.