What happened to turn Riot away from range/melee item separation?

Nothings 'turned them away' from it, they're just really careful about dishing it out.

People always decry that Riot stamps out diversity, and this is one place where they try to let diversity shine. Sterak's on ADCs, Iceborne on Ez, etc. Before they dish out targeted nerfs to dethrone that sort of diversity, they try softer nerfs to maybe let everyone use it. If it becomes a massive problem, then they'll act. It's an effort to allow diversity to shine.

Personally, I think Sterak's Gage is one place where they should draw the line and make it melee only, then rebuff it to it's former glory, but that's me.

The game would be boring as fuck if they did that, it's fun to try and see others come up with interesting builds. I hate laning against a gnar with a frozen mallet but I don't think he and other ranged champs should lose out on it.