they are blobby in the sense that their formation loses coherence which is fine. they aren't blobby in the mount & blade sense that they like to pack a few square feet so densely that sometimes units can't even damage each other for being to close.
In total war i believe the combat we see is mostly aesthetic, animations represent already resolved simulated attacks, not a physical simulation, so this problem isn't possible. worst case is some ugly clipping, or animations that don't align. it's really not a good comparison.
units in m&b are unaware of the space needed for their own weapons, no respect for even their allies need for space to operate, no concept of friendly fire. how much of this is possible to do without destroying everyones cpu's? I have no clue, but maybe some of it could be faked well enough.
one thing that might help is that it is okay to have units in the back ranks doing nothing, unlike how now charge results in a disorganized mess, and formations collapse on contact with opponents. deep ranks were noted to boost morale heavily, thinner formations might have maximized your active combatants, but broke very easily. they could relieve exhausted or wounded allies and they also provided protection in case of a flank.