I'd like to start by saying that I play a lot 3v3, both ranked and normal. Something that has become a problem ever since the map change though is the removal of Thornmail from the shop. I honestly don't know why it was removed but it really needs to be put back in. It allows people to play AD Yi and AD Tryndamere and essentially 3v1 a team by mid game because of the way the champs kits work. Randuin's is somewhat effective against Trynd, but it might as well not have passives against Yi. Thornmail is needed so you can effective counter-build certain champs, including this above two.

I'll probably catch a lot of flack, but I don't care. Something needs to be done about this problem. Thanks for reading.

Not happening;
To paraphrase RiotNome;

There's no direct counter play and it scales off your opponent's strength not your own promoting unskilled play.

TLDR; Sorry, but as per developer's words; no.

this is like asking, yea can you put eves stun back on her? it doesnt make strong,it makes her op.....

RiotNome's exact words:

1. It scales with your opponent's strength, not your own.
2. The gold necessary to counter it (on 3's anyway) far outweighs the investment to buy it.
3. It doesn't introduce any gameplay.

To counter the champions you mentioned, try Randuin's Omen or Frozen Heart.

I've always wondered why the item was so inexpensive. It does serve a strong purpose in some situations though. For the reasons I've mentioned, there is currently no items that help against AD Yi and barely any help against AD Trynd. Make Thornmail a lot more expensive, but put it back on the map.

could just make it proc on melee attacks only...

no no no, thornmail was complelty overpowered on this map, and it counters champs who allready strungle on this map anyways... melee and ranged adc