SC2 is very balanced when you look at the total game across a range of skill levels. Each unit is balanced around costs, attention, utility, requirements, and other units. Ex queens are awesome early game as they hit air, don't take gas or larva, and have high HP, but late game it's all about healing ultralisks plus anti air.
Roaches take a lot of supply, are armored so take more dammage from tanks and can't hit air which is their counter. They are also ranged so they don't share dammage upgrades with lings or ultralisks. Late game players will sacrifice them for more useful units and they need a larger investment in overlords.
PS: If you watch some high level games units generally have their time to shine as part of individual games progression.
Roaches take a lot of supply, are armored so take more dammage from tanks and can't hit air which is their counter. They are also ranged so they don't share dammage upgrades with lings or ultralisks. Late game players will sacrifice them for more useful units and they need a larger investment in overlords.
PS: If you watch some high level games units generally have their time to shine as part of individual games progression.