If only Paradox had named the succession to something other than "elective". Cause in practice it's more like heir designation with extra red tape and intrigue. Now you get tons of people getting hung up on "OMG it was never an elective monarchy!" etc. I for one like the new system, it feels like I'm trying to wrangle an ancient, bloated, corrupt and, dare I say, byzantine system of government.
I actually don't mind the general concept and a lot of the mechanics around succession. I do think you are right that people get a bit too hung up on trying to put it into a particular box when it is really a hybrid of heir-designation and elective. I do think it probably needs some adjustments, but that's generally true of new features. I really like that it doesn't weight electors the same.
My main issues with the changes are the things that lock you into specific decisions; being forced to use landed commanders; being absolutely locked into one succession type, especially since it prevents you from really using one of the best features of Hellenic. (I only see the Hellenic thing as an issue because it is so tightly tied to the ERE and the restored Roman Empire. I wouldn't care if it was just blocking a weird but potentially powerful combination.)
I would much prefer something more like the way powerful vassals and council decisions work in Conclave. You can put them on the council or not, there is just a significant but manageable penalty for not doing the correct/traditional thing (according to the in-game "culture" anyway). You can ignore your council voting against something, but it has a price. In the end, it is up to you to decide if the price is worth it based on your current situation. Neither option is always the correct/optimal choice, so it makes it an interesting mechanic. Even if it were harder to do than switching off Princely Elective as the HRE and caused your vassals to want to constantly faction and conspire to restore it.
The commander thing is almost (but admittedly, not quite) as bad as not being able to designate flank commanders with Autonomous Vassals when the game was young. I tend to not use landed commanders because they constantly want to leave my army to go lead their own armies and it gets annoying having to reassign them after every battle/siege. Also, I find it fun and satisfying to find a good commander and figure out a way to get them to join me. Being able to gain enough land to continually land new ones isn't terribly sustainable, especially if your commanders die often but have any family to inherit it (so you don't get it back). Something like being able to grant a barony as a viceroy might make that a lot more manageable.