This relates to Conflict Zone issues. Right now it takes federation Battlecruisers a few minutes to destroy a medium-sized ship. Even with all of its port weapons firing on it. I suggest the federation (and empire) refit their weapons to something that actually does damage, otherwise no one will take their presence seriously. Moreover, capital ships are basically not a threat to engineered ships. This kind of defeats their purpose, doesn't it?
Is your point of reference a conflict zone? If so, the thing is a capital ship is engaging multiple vessels, basically anything in range, and CZ ships are supremely tanked.
There is a USS where you can experience fighting a capital ship truly solo, and when you're copping all the subcapital weapons on one side simultaneously, you go down fast.
That said, in absence of any other sorts of capital ships, the point of them is, in my opinion, to support allied subcapitals, not engage hostile subcaps directly and alone... really their core combatitive ability is to engage other capital ships, in order to prevent them supporting their capital ships.
Now... if we're talking about the Imperial capital alone, that peashooter is on dire need of a buff, since the farragut trounces it every time (empire in general needs a substantial buff in warzones)