That is one thing that's wrong with our current patent system, when such actions are deemed acceptable. I'll bet you think Lemelson is a hero rather than a scam artist.
Nothing at all wrong with it. It's been a part of well established patent law for ages. Having it eliminates the need for an inventor to claim every theoretical possibility and keeps the patent office from being overwhelmed.
The memory manufactureres knew exactly what they were doing. They just thought they could do so and grind Rambus into the dust. That's not my personal opinion but a matter of fact. For more information on what actually transpired, I suggest that you read the 348 page Initial Decision by Chief administrative Law judge Steven McGuire of the Federal Trade Commission.