Mercenary exclusive item affixes

They are too rare.
Not only do you have to keep a kill streak going.
Not only do you have to get lucky that you spawn an infamous one.
Not only do you have to get lucky that its the right infamous one.
You also have to get lucky that he spawns with an item that sports a mercenary mod.

And after all that, if you got lucky, you can just pray that the item is actually salvageable. Since interacting with the recombinator is pretty much just deleting the item with massive odds like 0.2% for a 2 stat item.

Is there any plan to hopefully increase the rate at which they spawn with mercenary mods?

this is just classic GGG, they are so incredibly precious with rewards (that are actual immediate rewards and not a small probabilistic chance to become a reward after hundreds or thousands of pulls of the recombinator lever) that they often might as well not be in the game.

Which to me is a game design failure. The actual game is probabilistic manipulation and the win condition is X million monster kills and x thousands of crafting attempts.

No one at GGG ever wondered if its fun that the win condition is to gamble enough times to eventually hit your crafts while completely ignoring ground loot.

I want my dopamine from killing monsters not hitting the 3% chance on a slot machine lever pull. But I guess we'll have to hope POE2 can manage it or maybe Chris's game.