ADCs having defensive items isn't supposed to be a problem
They've always build defensive items as 5th and 6th item. Don't get mad NOW.
In particular since Sterak is supposed to synergyze less than, say, GA and Spirit Visage with an ADC's build. The shield from Sterak scales with max HP, that ADCs don't build. The sustain increase from Spirit works on lifesteal. ADCs are drain tanks, and Sterak gives them a shield and HP. A shield is better than just flat HP, but still worse than resistances to have your lifestolen HP matter more. GA, conversely, gives only resistances and a passive for starting over to do DPS. Sterak's passive gives base AD, which ranged champs have lower than melees. Not enough to make it more worth on melees? Increase the difference further (by substracting 8% of the AD at lvl18 of every ranged champ) and give more attack speed to rangeds if it's too big of a nerf.
If Sterak's a problem, it's due to the kits of the reworked ADCs, the itemisation for the opponents, and the teamcomps. Not to it being available to ranged champs.
is seriously underrated right now. More people should use it. It's been nicely buffed to 60 of both resistances and right now with all the flat pen around and not everyone building
items, resistances are pretty valuable.
I'm sure once people realized that it will become much more meta than it is right now.