Because why not?

I use a Tank Build (Heavy Guns, Heavy Armor, High DPS, Low Mobility) with Ultracite Power Armor.

It's essentially a Penalty to use Power Armor when every other Griefer runs around a light speed with whatever the latest 3-Star Legendary Armor is the meta at the time, especially with the eternal battle of maintaining Power Armor with scrounging for Fusion Cores and Repairing it, while Mr. 3-Star gets better buffs and DR and just has to slap some leather on it every now and then.

With the addition of Backpacks now, Power Armor doesn't even have the benefit over Carry Weight. How can someone sew a ton of pockets to a piece of metal and pull on their back-purse and have the same (if not more) carry weight than a literal mechanized exoskeleton? (Even with PA Mods to Increase Carry Weight).

Not to mention how horrific Power Armor is in PvP. A man with essentially a Legendary Leather Condom takes less damage than a literal mechanized tank? In what world?

Obviously this is all gross over-exaggeration, though I feel are all realistic concerns.