Mostly a preference because of the Chad Drones, but since Warriors are said to be an evolution (or natural lifecycle progression) of Drones ("aged Drones", according to Cameron, but that contradicts Scott's original comment that Kane's Son was dying in the Narcissus because of a short lifespan), my thought process is that Drones are meant to gather hosts (overpower/carry/disable, like in Isolation) and build the hives, so they'd be larger for those tasks.@Jormungandr
Question! Any reason why you prefer Drones being taller/larger than Warrior Xenos? Because in most media it's the opposite.
The only exception I can think of is Alien Isolation and it's giga-chad Drones.
In contrast, while Warriors could do that too, their job is to, well, kill and eliminate threats to their hive, like the Colonial Marines and armed colonists. They need to be more agile, compact, and powerful, like a snake ready to strike than a hunting spider waiting to pick off a victim.