Supporting weapon-swapping would require a lot of work. One of the reasons we were able to make the wow classic site at all is because we re-used a lot of the code from the retail site. Introducing the idea of a player using more than one set of gear at once would require structural change to a lot of back-end code. I don’t think it is feasible to support that, unfortunately.
We’ve been trying to be very up-front about the classic site and what it is/will be. From the start, we’ve said that we won’t be making a simulator for classic. I don’t see that changing, based on the number of people using the classic version of the site. I appreciate that there are a few people who would love to have a full-featured simulator for classic - but there is no way we’re going to have time to make that happen.
You said the suggestions you get when the optimizer is pushed towards “mostly DPS” seem to be good. Why not just use that setting?