The Rams built up a belief system in Landman, that he is a good starting linebacker, in that phase early last season where he was playing over his head. Then they rushed to pay him. It was a mistake, and since that time he has reverted back to who he was. He was always going to revert back to who he was regardless of whether they paid him, however if they hadn't paid him they would have addressed ILB perhaps.
But they didn't because they believe in him. It's stupid. All teams do this kind of thing, as they're run by people and people can't help but make mistakes. So these things happen and it's not like it's a massive financial mistake to play him. But the impact of the mistake was they overlooked that roster position and as a result it remains a need as it always has been under McVay/Snead as a roster building team.
All this aside we have won in spite of ILB. I get that. But one of the reasons we're fragile on defense is the hole we have in the roster quality in the middle of the field.
The future of ILB is speed and tackling in space, and ability to snuff out running QBs or at least limit them. Days of heavy duty early down backers who fill downhill are gone. They're easy to get and put on your depth chart, but at the top you need a couple who don't come off the field on passing downs.