I discourage but do not forbid* the swapping of a WR slot for a Flex spot in future years.
*obviously I can't explicitly forbid anything, I just hate change but I'm not gonna get all uppity about it if everyone else wants it
this is where I hypocritically laugh at moot for playing two tight ends after bopping #strongs league last year with Gronk + post-injury Reed
I actually do like having three WR-only slots, since it's a lot deeper than RB these days so sometimes it kinda makes you scrounge for a half-assed third option to plug in kinda like how you often need to do for RB if you didn't draft two studs early. With only two WR slots, it's too easy for everybody to have two really good options so there's less thinking and turnover. On the other hand, I like having a Flex spot too because it makes the draft itself more challenging by forcing people to directly compare the scoring potential of players in different positions instead of solely going off positional tiers.
(This is not me advocating for simply adding a Flex spot and having both 3WR + Flex.)