That was part of my thinking, yes. But also, achievements are related to various things, and I think it adds more to the wiki, as the achievements section seems to go largely ignored, so putting it on the pages makes navigation easier and draws attention to parts of the wiki and the game that people may not otherwise have realised exist. Wikis are intended to disseminate information about their topic, but the achievements are largely hidden, existing but not being disseminated. Some pages already have the achievements in the Trivia section, but not many, so it's very inconsistent and not very informative, as one could go from a page with the achievements listed there to a page without and assume that the latter has no achievements related to it, whereas it could be something like Possession, which actually has five. Having a section for it everywhere that's relevant does inform. However, you will have noticed that I've put it near the bottom of the page, above only the Gallery and Audio sections, so those that do view it as unnecessary need not read it.
I can see your reasoning to some degree. I still have some criticism on how this was carried out, though:
I find it generally superfluous to point out achievements in this fashion (or at all) which will inevitably get unlocked while playing because the relevant action is mandatory. This applies to the achievements you added for Emily Kaldwin, for example. You can't miss those, so drawing attention to them is unnecessary.
I can see pointing out achievements that are unlocked for actions you would not necessarily think about, like climbing on top of Kaldwin's Bridge, staying in a rat tunnel, or removing whale oil tanks form security systems, since those can easily be missed otherwise. As you pointed out, we have some of those mentioned in the trivia section of their respective pages. I am not generally opposed to add related achievements to pages, but I would prefer to keep the method that has been utilized so far. Giving them a mention in the trivia section also gives them a little bit of context. I think "Collecting all 11 paintings will unlock the Art Dealer achievement" in Trivia flows better with the overall page than some "Related Achievements" tossed at the end.
If you are planning to add more of the achievements to pages, please put some more thought into what you put where. You might have noticed that I removed some yesterday that made no sense, like the two drop assassination ones on Supernatural Abilities. Okay, on second thought, Corvo will probably have to use Blink to get up there, but wouldn't the more obvious spot to add them as related be the places from which Corvo and Daud drop?
I can see what you're saying about the unavoidable achievements, but given that some are up there, I thought they may as well all be.
The reason I didn't put them all in trivia in the first place was because I started this idea on the Possession page, which has five achievements, and I thought that that looked bad when all crammed into the trivia section. However, I can see that it doesn't look so good for the pages with less achievements, so I'll go through and move them all to the trivia section.
I wasn't sure about those achievements from the beginning because, while they rely on supernatural abilities to achieve, they're not directly related to the abilities. I decided I may as well add them and see if anyone removed them, rather than not add them and find that everyone agreed they should be there. The reason they're not yet on the pages you suggested is that I haven't got that far through the achievements lists yet, and stopped adding them while this discussion was taking place.
Please add related achievements only to pages that they are obviously related to. I think people should be able to make the connection right away, not through thinking laterally. That means, the two drop assasination achievements on the locations, NOT supernatural abilities. Kill someone with their own bullet on the bullets page, not sword. I think you get the idea.
Edit: I fixed the pages you did already to give some examples on how this could look. I removed some, and implented others. Note that I did put some of them not in Trivia but in other sections. You could argue about that being inconsistent, but I went by finding a spot to add them where they would flow well, not by consistency at any cost.