Would you. Consider seeing up defensive positions engineer jobs? Because pios can do that and CE cannot.
But they do their engineering jobs just fine. They have different types of mines and explosives - not a big deal - one player prefers minefields+telles, another prefers regular mines. One player likes cqc and more risk because of it, another prefers long ranger squad with less vision.
Sandbags as well as bunkers (yes they cost extra but it's an option)
Ability to build sandbags should be given to grens just like it was given to conscripts. Pios can build them and it makes them 'overworked' and makes it more difficult for grens to use those sandbags. The fact that pios not grens build them is actually a nerf to the whole faction. I'd move them to grens immediately but a lot of allied players are afraid of it (but it is ok to them that cons and UKF inf. can build them!)
Bukers were supposed to be a faction feature. They are, however, not used by many higher skilled players as they are just too expensive and can be too easily destroyed because they are stationary. I understand they can build them just like grens, but it shouldn't be reflected in the price in this case. As Soviets you don't need to retreat your units to build healing.
Pios cost more because they do more. It's not negotiable. Do more= cost more do less =cost less pios do more = cost more CE do less = cost less. There's more to the game than JUST repairs late game.
In my opinion they simply don't do more. They are just different. The price should be the same or you destabilise lategame. A unit so cheap and so useful just shouldn't exist. Maybe if they weren't given extra repair speed after they receive sweepers...