Why does Magento have to toggle his shield and can't hold?

I main Adam Warlock but Magneto is my favourite tank.

Both Doctor Strange and Captain America have a setting that allows them to hold their shield out instead of toggling, but Magneto doesn't. It's quite frustrating as I end up using way more shield than I need to, meaning I'm just wasting shield energy and decreasing my overall shield effectiveness. It doesn't help that the shield already has such a small duration, so saving every little bit of energy counts, and a setting to hold shield would really help. It seems so easy to implement as well- they've already done it for Strange and Cap so they can just...copy the code and add some minor tweaks and whatnot.

The only reason I can think of as to why they've not done so is because they intend you to use the whole shield duration at once, which seems kinda silly and stupid. But I'm only Platinum so I'm honestly open to any corrections here. :D

I initially thought it had something to do wirh the fact that there's a delay between when you close the shield and can open it back up again, unlike Strange who can close and reopen instantly, but the Cap also has a delay so I don't really know-

Now obviously this can all just be a skill issue and I should learn how to play well with toggle shield, but it just seems so silly why they wouldn't add this and it would be super easy to add and would help loads.