I think some people are mistaking the military development lifecycle with civilian development lifecycle.
I was watching a documentary about the AH-1 Cobra today. The original design was created in 1967 as a viable attack helicopter for use in Vietnam. It's till in use today as the AH-1 Supercobra.
Earlier I saw a similar documentary about the A-10 Thunderbolt. It was originally designed in 1970. It's still in use today. According to Wikipedia it's not going to be phased out until at least 2028.
The difference between the time when those weapons were originally developed and now comes with advances in armament strapped onto the machine. Things like 15in. rocket pods, hellfire missiles, and smart bombs were not around in the 1970s. Instead these things were designed to augment the old machinery so that the United States could have a modern armament without redesigning entire systems.
Now if you look at space, it's really a military place. It's not like designing a car. You change the way a car looks and the car still works the same way. It's a rather basic machine. You could think it would be easy to add a fin and a gun to an A-10, but in reality then you have to add and program new controls, rewire the system, and take into account the change in aerodynamics.
We're in space now. That doesn't mean military hardware is any easier to make or change. What is likely to change about an older defender? Armor plating. Powerplants. Armament. Basically everything we've changed. The fundamental ship shouldn't change that much. It's what it can do that counts.
The Mk IIs make a lot more sense from a realistic military life cycle than adding new ones. Really, they do.
[8:32:45 PM] Dusty Lens: Oh no, let me get that. Hello? Oh it's my grandma. She says to be roleplay.
[12:49:19 AM] Elgatodiablo: You know its nice that you have all that proof and all, Bacon... but I just don't believe you.