I think they should be considered on-topic. In my view, the scope of the site is much wider than "people playing chess in a traditional sense" and can include many things unrelated to play, such as history, equipment (including software), cultural references, etc. It's not like this site is under a deluge of questions, and in fact people often worry that there are not enough questions, judging from discussions on chess.meta.
The What topics can I ask about here? page describes a relatively wide scope like the one I allude to above, although it calls some topics "gray areas". Regarding engines, the current wording is "Chess-specific questions about programming a chess engine or other chess software are welcome". So engines are on topic, at least if you are programming them. The wording is too qualified in my opinion; I see no reason to exclude questions about using chess engines.
I'm sure there are many questions you don't care much for, just as there are questions I don't care much for, but I think that's perfectly normal. I'm actually surprised by how large a fraction of questions asked here I consider interesting, compared to other StackExchange sites. Consider StackOverflow, the mother of all sites. I'm a programmer and yet I find 99% of the questions there to be utterly irrelevant to me (even browsing through specific tags doesn't help much). I don't even try browsing through the site; its main use (and it is a great use!) is to find answers using Google.
If we exclude such questions here, where would they go? A chess programming StackExchange? Considering that the chess site is already marginal in terms of traffic, why split it? There are already people who suggest the chess site should be merged into the board games site, something which I would truly hate!