What I gather from what RDJ said is that Tony’s newer suits are more about doing whatever it takes to protect the people around him. This is evidenced in IW where he says the new reactor was made “to protect us, the future us’s, and nothing else.” The 50 and 85 are probably essentially the same suit to RDJ, especially considering the 85 wasn’t even a thing on set, and their functionality is very similar anyways.
The first suit was built to protect him, get him out of the cave and bring him back to his life. He made the last suit able to sacrifice its user’s safety for the sake of “the community.” An older model might have rejected the use of the stones as they put the user in danger. I heard someone ask why he didn’t have the gamma resistance of the Mark 26 in the 85, and I think the answer is that those kind of protections aren’t even on his mind. He’d rather focus on adding 15 new weapon combinations than any more user safety measures.
The evolution of the iron man suit has consistently shifted from protecting Tony Stark to purely protecting others. The mark 6 was made to save his life, then the mark 42 was able to assemble around pepper. The mark 44 was made to protect people (and banner) from the hulk, and the mark 47 was sent to save peter from drowning. The mark 50 actively endangered him by redirecting nanobots from his helmet so that he could continue his fight with thanos, and the 85 actually killed him so he could eliminate the threat of thanos entirely.
Obviously he’s not going nearly this deep into it all, but it’s really cool to hear RDJ even talk about a specific iron man suit. It lets you know they don’t all just blend together to him even after all this time. Very Tony Stark of him.