Having range is such an inherently huge advantage, there's no reason to further punish melee champions by fighting against a ranged champ that is able to heal so much from such a safe distance.
I think that would be a bit much
However, having the effectiveness of lifesteal scale inversely with distance could work
Then if you take risks as a carry/are a shorter range one you can still drain tank a bit
You're fighting a hopeless case
This has been suggested many times, but Riot won't ever do it because they want Ranged ADs to be overpowered
There's a reason the class has been mandatory for 4 years now
Because melee carries having better steroids, more mobility and often more CC isn't enough of an advantage against ranged champs who's only real advantage is their range?
They really need to do this. D ring casters can be a pain but they're not nearly as stupid to play against as ranged d blade users. With a doran's blade you can easily freely auto more than 2x your opponent who has to actually stay away from the wave because they'll receive harass. Lategame teamfight dps specialists should not be able to faceroll fighters in lane like they currently do and this wouldn't actually stop them from being played because they're so mandatory lategame, supports would just have to prop them up early in a time of actual weakness which adc do not currently have.
But this will never happen because over the last year riot has been doing everything they can to balance around low elo adcs and make people that can't kite feel like doublelift.
Ranged isn't a huge advantage, just learn to play melee champs better if you want to play them against ranged champs.
Ranged champions do have an inevitable advantage over melee champions. It's not so much a balance issue as it is a general concept of RPG games. If they punished ranged champions for being...well, for being ranged, how fair would that be? Instead of punishing ranged champions for doing what they do, they should give melee champions more options for dealing with them, and for the most part they have. Many melee champions have some sort of gap closer or "get over here" ability (Darius's Apprehend, Blitzcrank Rocket Grab, just to name a few), and there are items you can build to help you deal with ranged champions such as Randuin's Omen and Thornmail. However, I do agree that there should be special options accessible to melee champions only to help them deal with ranged champions, such as an item that mitigates projectile damage OR bring back the old passive of Randuin's Omen on a different item. It would be a nice way to let ranged champions do their thing while providing melee champions a chance to shine.
Normally melee are supposed to have some benefits from having low attack range (Like bonus innate tankyness or lower manacosts), but why not ?
DotA is doing this for years (Melee have better odds on some items) and it works well.
I think they tried something like this before but made ADC almost unplayable vs like double bruisers
Originally, it wasn't as big a problem because the adcs weren't really mobile. I think it has become a much bigger deal with champs like lucian and kalista.
It's not just a problem in the bot lane either, ranged top laners are starting to crowd out melee champs, and even in Korea they sometimes run ADCs like Corki or Ezreal in mid lane because ranged AD champions get so many nice things.
This sounds like a reasonable trade.We don't need ADC healing,as much as late game tank 
,in the middle of a teamfight.
Why do people act like Thornmail is completely invalidated by life steal when it's the other way around? It's as if they think they can actually 100-0 someone with Thornmail's damage alone. Here's a hint, If you are ever in a situation where you tried to 1v1 an auto attack champion, bu they just barely survived then Thornmail will sove all your problems.
TLDR: Thornmail is a fighter item, the only full tank it works on is Rammus.
Also, the real solution is just to add a couple of powerful melee only items, but rito seems to have left of on that during season 3.
How would this work on Quinn? Jayce? Nidalee? Kayle? Elise? Aatrox? (R)
or you could just get a thornmail when you feel the enemy ADs is dealing too much damage/lifestealing too much.
