It almost feels like I could be making my marines worse in most even engagements by stiming.

The only real advantage is if I have a unit count lead or while escaping.

What reason do you get reduced range while using stim?

to penalize the increased attack speed and movement speed, apparently taking away hp was not enough

10 out of 10 times i will not go rines, id rather invest in a hero, nix, colo, tass, festor, hb, or dt, they all counter rines in some way.

9/10 games i will win without rines
the tenth game i probably afked

AFAIK, there were a big change in marines. The minor upgrades never affected their stats as they once did.

So Relic thought the range reduction was needed to prevent snowballing.

Stim isn't worth unless you have melee or its later in the game after you have your ranges/minors/epic. Stim addicts minor makes it considerably better if you have melee though, since it boosts movespeed.