I have to disagree, and whilst I'm not a huge fan of them myself, I can see the reasons and benefits. Chester's was a good display, it did boost visitor numbers, they didn't look as bad as some I've seen and they had a good amount of educational material.
If somebody can give a productive argument against them other than personal opinion, then I will concede, but I can only see positives [I'm going with Chester to defend here, since it's the collection I know best]:
Cost = not a valid argument, they started making profit on the dinosaurs pretty much straight away. The income from them far outweighed the cost.
Space = They were put in an area of the zoo that hasn't had animal exhibits for years, and that to my knowledge won't have any enclosures on it in the near future.
I dislike them, yes - but I can't think of a good reason that Chester were wrong to have them.
[Twycross could be different, in its current position it could tip the balance either way. I would argue that a lot will depend on their success].
You're possibly right, maybe i'm biased because i hate the things, and since your argument isn't based on liking them, your points are even more valid. I haven't tried to argue that they don't make money, just think it's sad that they are a necessary evil! I just feel the animals should be enough of an attraction alone, surely they are still the reason most people go to the zoo? If not why don't those people go to a theme park or Go Ape or just the local park playground or indoor play area? Certainly some of these would be cheaper than a day at the zoo!