Saint, I'm not thinking of the design change as incorporating countermeasures, actually. I'm thinking of the visual change in proportions/style, for example, as simply a factor of the "A.N.B.E." and how it will take everything "out of kilter" as you move forward from that point.
Less "Wow, we went through that and we have to build this" and more "Well, I was going to build this (1964 TOS E), but I suddenly had a new idea to tweak it like this (2008 JJ E)"
That would mean it would also come to be titled "Constitution" Class by the Federation, but it would be an ANBE-Constitution, if I'm making my point well enough.
It recognizes that they aren't the same vessel, but they are the "same ship".
It's like Geordi: "It's like...I'm there, but I'm not!!111"