I completely see where you're coming from, and there are a lot of negative examples of this. However - in this specific case, I think it looks like an accurate representation of the leaps in technology between TOS and TNG. There's, what, 70 years inbetween? You would think the original Enterprise would look as antiquated next to the Enterprise D as it does in the episode.
My problem isn't that it doesn't look antiquated compared to the
Enterprise-D, my problem is that it looks antiquated compared to the current level of technology and expectations. They could have taken the bold risk of designing a "new-old
Enterprise", which would have avoided the scene in
Enterprise where the alternate universe crew found the
Constitution-class USS
Defiant and it looked like they took 50 steps down.
Yes, you could have kept the same general designs as Zare noted, the thicker bulkheads, the smaller viewscreens, but updates some of the horrible 60sisms.