Yes and no. Basic mechanics shouldn't be behind the walls of perks Agreed, however I prefer perks that add some content/mechanics to game rather than giving us X% boost to Y action, which is simply boring.
In my case the trade perk is merely an upgrade over basic game mechanic introduction, but I don't mind either of choices (just add bartering fiefs to the game).
you want virtual feelings of progression, regardless of wants and tastes, that makes for poor design for any sandbox style game. Fief trading should be fine, but the value weight should suffer heavy penalties if you try to pull that off with low trading / without perks.
IE: You hold Sanala with the highest save prosperity, pull the bartering for Varcheg, no perks = guy demands sanala + 1 castle or 2 or even more for to trade for his crap town that has low prosp and generates crap income.
You do the same with all perks and sky-rocketing Trading at 325, you manage to trade a high prosp castle (1k) for Varcheg no problem.
IE2: You wanna purchase Sanala with highest prosp in game - No perks barter = 10m 15m even - With perks 2.5m to 5m
Besides, bartering with lords' a waste of time and resources, other than trading fiefs they hold absolutely nothing I want (talking for myself but I believe it's the same for everyone), and even if it's something "okay-ish" like a rare armor or weapon, it's overpriced. You always gain more by doing any of the alternatives (farm the item, travel to towns / villages that produce said item / anything). So far the only 2 functionalities bartering hold are trading fiefs (first and foremost) and bribing the dumb ai to join your realm to make "numbers" (lord vassals are virtually useless for anything but numbers) - Having said thing locked away's basically turning half of the bartering usefulness for the player into a grind-fest. Reaching high trade's such a chore that most if not all of us exploit to boost it or use mods to increase XP gain.
The Click-Simulator that the game becomes when you feel the need to boost tradinng's excrutiatingly boring, and a unfun time sink. So much so that I've been using auto trade since it was first released for that reason (because I hate exploiting and wasting my time), yet I still crank up the dials for XP gain with other mods to make it less boring.