I do not know how Itch staff processes those feature requests, but I would assume it is easier to have a single request for a single feature instead of giving them "a list".
And I disagree. A reverse order option for collections would enhance the usage of Itch for everyone using collections. It would make them usable as an actual watchlist. Without need to scroll to the back everytime you want to play the oldest game on your watchlist.
An exclusion filter is often lamented about in comments, but as someone who has ability to use a lot of different exclusions, I can tell from experience, that it does not give quite that enhancement. I just do not need it, and my project exclusion is so efficient that it can spoil browsing experience. It is one of those features that only look good on paper. (My project page has 3 different helpers to exclude things. And the most powerful can ignore accounts and games at the press of a button. If you weed out the top pages, they stay weeded out. A tag exclusion is misleading, since it depends on the devs using those tags in the first place. Also, interested users can find this in community and use a bookmark for single tag exclusion.)