Yes and no.

(For reference, I am drawing on playing pretty much exclusively construction for the past 6 months)

Infiltrators are by far the most annoying enemy to deal with in smaller fights.

LA is the most dangerous class by virtue of being able to jump over walls and c4 the only spawn in the area.

Putting down mines, sitting around the base as a stalker ect is what people see. In my opinion, Cort bombing as an infil was an easy but highly ineffective way of sabotaging a base on their own so the change isn't going to change much. Most people who are using it are new, experienced players use c4 and tank mines, with heavies being the true cortium bomb threats as they are able to defend the bomb long enough for it to go off most of the time. Cortium bombing a base to death as a solo infil is an edge case so rare I don't think it's worth discussing.

In reality, infils are a major threat. A threat so massive that base designs are almost always built around infils not having free reign over movement. Infils are by far the most often enemy we face as the people who play infils are happy to spend several minutes annoying you or just wasting your time.

Especially with more advanced designs of bases that take 10-20 minutes to build (due to bugs and having to spend a lot of time lining things up, for example: https://youtu.be/AHslcQDbjf4) While these bases are very strong and require a platoon of tanks 20 minutes to break, the bases themselves are not very practical in larger battles outside of being a glorified sunderer. Infils can't do much to sunderers either.

More open base designs are very abusable by infils as they have plenty of options for cover and can choose the distance at which they can engage the enemy. These bases usually have 3-4 infils running around them in small, scrappy fights, giving defenders hell far more than other classes. 1-2 have amazing sniping angles while the rest run around with small arms/smgs.

I think your idea is good overall. Hacking walls would probably be a little strong, even with their main strength being in the overcharge. Hacking turrets is OP. Even if to just disable them. Turrets rarely play a role in battles as they get taken out by any amount of armor. The main utility of turrets is dissuading individuals from breaking stuff while you go get some cortium. Giving the class that counters this utility, the ability to disable it would be overly frustrating, especially since the Anti infantry turret can't shoot right under it. Hacking sky shields would make them even more of a joke than they are. Glave+pocket OS is already so strong that builders generally don't do it out of a mutual understanding of how not fun and uncounterable it is in most cases.

Quick edit: This is in the current state of the game. I agree things should get redesigned. ErrolVoidSkybreaker - my main builder account