I can only agree with you, because of the two posters you're referring to I'm the one advocating for talking about both.I think both perspectives are correct.
Imagine a friend takes you to dinner and pays the bill. (You don't see the menu or the check.) That night you jot down your thoughts about how the meal tasted. The next day, you friend tells you how much it cost, which turns out to be twice as much as you would have guessed. You do not go back to your notes and change your opinions about the taste of the food. The food itself "was what it was."
However, if you later are talking to folks about the restaurant business and what restaurateurs should or shouldn't do, you might want to think about the bad choices of that particular place you visited and how it could be much better managed. You might even decide not to go back.
The first scenario is like talking about the attraction itself. Is it good? Does it fit? Is it innovative? Does it have AAs? Will I want to go back? The second scenario is more about what could have been. How could that money have been put to better use? Was it worth it? I think it's fair to talk about both.
In fact, I made a very similar restaurant metaphor to @Incomudro a little while back, in reference to this exact same topic.
I can't imagine why anyone would suggest discussing the cost of the attraction amongst people who know it isn't permissible because not everyone knows it. That it shouldn't factor in to our opinions just because it doesn't factor into everyone's opinion.
Most guests don't know that the Yeti's been in B-Mode for nearly 15 years. That doesn't mean it isn't objectively an example of bad maintenance. And it doesn't mean we can't or shouldn't discuss it amonst us who know better.