I think one of the main problems with Stellaris is that even YOUR race doesn't seem to matter too much. There's a few different interactions, a few caveats on how you set your colonies, but it's essentially same-old-same-old every game. You'll get along with some neighbours better or worse, but the means to the end seems to be the same in every game. Races are just slightly different blobs of friendliness/unfriendliness, colonies/planets are just good/bad/unavailable as pop centres, and your corvettes will take care of them all eventually, regardless. Maybe it's a balance thing, but it ends up being a bit bland.
Compare Alpha Centauri. It might not be a perfectly balanced game, but playing as each different faction actually did feel different. Build up or wide, outproduce or out monetize or out research or outfight your opponents. Government types were just bonuses, but they would have a definite effect on how you played. These tiny little bonuses had large effects, not only on diplomacy, but on your overall "grand strategy". Playing as Hive or Morganites or University or Fundamentalists all had "their thing", without them actually being that different from one another. Maybe it was because they were human, so you could relate to the differences in their outlooks and styles more easily, but they never really seemed bland or uninteresting, even when you were just steamrolling through them, one after another.
Compare Stars!. Each race you created would have a definite playstyle. From acceptable planet types (leading to intersettling agreements or disputed terrains), to mining types, to tech proficiencies, to hyper-growth/hyper-proficiency economies, every race has a "thing to do to succeed". Every Primary Racial Trait gave you a thing you were good at. Warmongers would zerg, Space Demolitionists would litter the galaxy with minefields, Interstellar Travellers had amazing defensive mobility, Super Stealth would appear from seemingly nowhere, and Hyper-Expanders would expand quickly at all costs. And therefore, you'd approach each one slightly differently depending on your own racial advantages, even if it came down to tonnes of warships and bombers in the end. Diplomacy was because of your race and theirs, what you needed could be vastly different to what they wanted in an area, and strategic advantage was exactly that. Not a slightly differently flavoured blob, actual differences in what was good for you and what you could do compared to them. So diplomacy followed on from there, not baked in as a like/dislike system. Considering you only got a few racial advantages, maybe a couple of tech toys, and every race was generic as hell, they all played very differently. Everyone would expand at all costs, but wars and interactions would have large consequences, and you did those things differently than your neighbours did. Even the galaxy that you played in was vanilla as hell. A wormhole could be a boon or terrifying or ignored completely, an opportunity to setup a pocket empire, or a backdoor directly into the heart of your own defenseless worlds. A tech trader was pretty random, but could give your entire empire another niche in the galaxy with what you got from them. These were the only two "events" in the game, but they worked.
Perhaps there's not enough actual ingame mechanics in Stellaris for differences in playstyles, races and strategies to really matter. Cities in SMAC depended on the terrain, your tech, your wonders, etc, as extra variables, along with customizable units and government types. Where you fought was just as important as what you fought with. Stars! had minefields, scanning/cloaking, mineral types, habitability, stargates and ship-type niches, all giving different ways of changing the playing field. Fleet design was both an artform and a science, and utility ships really mattered. Stellaris doesn't seem to approach this level of complexity, even though these aren't exactly complicated things for a 4X to have. There's grand strategy in it, but very few ways of truly altering the strategic or tactical playing field at a smaller level, other than bigger numbers and some rock/scissors/paper in fleet design. It's kind of lacking if it wants to be both things. Not enough mid/end-game events/outcomes for a satisfying grand strategy, but not enough strategic/tactical options for a 4X. Mostly due to a lack of mechanics in the smaller or bigger picture to have either.
So I'm not sure if heaps of different events will help out Stellaris. It certainly can't hurt, but I'd rather see races and government types actually mattering more. Tech toys really altering things mechanically, not just bonuses. Rather than being slightly better at something, actually being good at it, in a way that affects how you play the game and your objectives to win. Even if you've got to be bad at other things to be good at that one. But in a way that isn't just a +/- bonus, something that does effect what you do and how you do it. Bonuses can achieve this, but they don't seem to have achieved it with their current race creation stuff.
They did FTL space travel types "right", if only because they actually do affect how you play a bit. The rest seems to smear out and doesn't seem as characterful. Balance is a bitch, but things don't have to be perfectly balanced to be interesting and fun. THAT'S what patches are for, not adding in this sort of stuff to a game (that certainly should have been there to begin with). But hopefully they do add it in, be it by patches or DLC. As well as tonnes more events, because "Why not?".