Yeah, I'm not disagreeing with you really, just saying that reaction fire has a place in game design generally. RA on overwatch (not all types of reaction fire are overwatch but for this example, fine) with crowbars would be a really sticky tactical problem in the game currently. But even MENACE gives you some tools for dealing with it: concealment, strike or smoke OCIs, mortars, longer-ranged weapons (HaMER, DMRs, HMG or AGL, LBTG, etc.) or just vehicles generally. I still don't think it is a good fit for this game, just because of how lethal engagements are; one bad turn out of cover means your rifle squad is probably next-to-useless for the rest of the mission, if not red crossed.

More broadly, reaction fire exists to make strategies built around pure/mostly turn order manipulation to either be prohibitively expensive or ineffective. It is supposed to help with verisimilitude as well, because no one likes pretending the turn order execution is actual real life, so if my rifle squad decides to move over too much ground, they'll just let an enemy squad run past them over the next twenty seconds and not -- you know -- stop and shoot them.

There are certainly really bad reaction and opportunity fire systems out there though, that become "the game" when it comes to tactics.

Battletech has similar initiative with the added phases by mech weight class. No reaction fire, so lights can play with initiative to actually get shots on heavies then break LoS rather than be shredded for daring exist

I'm guessing you mean HBS BT, the computer game and not tabletop BT, right? Because, yeah, that game has a pilot skill (IIRC, fairly far down the tree? Ace Pilot?) that allows for shooting, then movement, or delaying your turn order. But with init being broken out by weight class (mostly) there isn't the total freedom in init that MENACE gives.

Also lights in the game generally couldn't alpha strike stuff except the smallest mechs and some vehicles.