Looking past the initial shock, I've come to the conclusion that Samurai's guaranteed crits, disregarding the as of yet unknown potency changes, are a very healthy change not only to the job but to the party buff meta as a whole. I have multiple reasons that I'll go over in excrutiating length, starting off with simply how it will feel while playing.
As many of you reading are keely aware, Samurai is a job that has a few facets to its "identity". One of them is the big single skill numbers that it churns out regularly. For a lot of players, seeing a massive number pop up on the enemy is satisfying. Ever since Stormblood we've seen Samurai gushing over how high they can hit with Midare and now Namikiri. What's not so fun however, is seeing those big numbers fail to be BIG, because you didn't land a crit or direct crit. I've played with many people who've complained about their awful RNG completely screwing them over. From a simple emotional standpoint I believe players will find these crits very satisfying, especially with the potency adjustments to offset the loss of Kaiten.
Ensured crits don't just improve the "feel" of using these skills, they also smooth out the damage over the long course of a boss fight, particularly in Savage and Ultimate settings. With the harder focus on 2 minute windows we've been seeing from the development team, it's more important than ever to have good luck during these burst windows. The modifiers for crits, direct hits, and especially direct crits scale enormously, especially so while under the effect of raid buffs. I believe the high scaling in general should be addressed by the balance team but that is another post altogether. Warrior has proven the stabilizing effect of guaranteed crits, with the much lower damage variance compared to all other jobs including other tanks. Performing well due to skill is satisfying. Not performing well due to poor luck is frustrating. Going forward, balancing these two concepts will go a long way, and this change is a step in the right direction.
On a very different note, Samurai's new gauranteed crits will also serve a role in stopping a "stack buffs on the strong guy" meta. I used to play a game called Maple Story where this was a very pervasive problem. While it isn't present to the same degree as that game, I see it here with Samurai. Though Black Mage's personal damage is just as high it is more spread out, allowing them to contribute roughly equally in burst windows. Samurai however concentrates a lot of its damage in burst windows. Other jobs gain a disproportionate amount of damage with their buffs if a Samurai is in the party, compared to for example a Reaper. rDPS is misleading in this sense. While it does reflect the damage a Samurai does, it does not show the damage their party gained from the higher personal damage. I ran some numbers out of curiousity and I'll share them in the next post