There's some course correcting, definitely. Doesn't mean I want them to add more!
There's another way to look at it. I mean, yes, it seems daunting if you think as every new addition as a distorting factor you have to compensate for. But, really, even if you are tailoring to your party, and even if you're trying to impose some balance upon them in the process, it's one effort, and only whatever they've done to break themselves is relevant - and that only in a net sense of how overpowered is the party all together, and how wrecked is their intraparty balance relative to eachother.
Turning the dial up to 13 instead of 12 to keep them challenged isn't that much more of a burden. And if the character that goes wild with increased effectiveness due to some unanticipated combo just happens to be the one that was languishing before, hey, your life may be a little easier. You never know.
The level of burden it might add would depend on how much they added to the game and what it was.
And how much of it impacted your party.
For instance, I really want them to be careful with feats. I mentioned earlier in the thread (or maybe it was another thread, they're blurring a bit) that I don't want the kinds of feats that remove the inherent limitations placed in a class. 3E/Pathfinder was rife with these kinds of feats, and I feel like they're looming as a possibility as soon as feats are expanded.
I can see that concern. I had a problem with a feat in 4e, that way, it removed OAs for spellcasting, just, like that, a tactical dynamic that was, really, classic to the game (mr mage should stay outta melee), gone. Obviously not a concern in 5e, but I see where you're coming from.
But I don't have an issue, personally, since I simply don't use feats unless I'm running AL (which I have been doing less of over time).
As for closing the door on non-core material...in the past I've not always found it to be easy.
Well, it was hard in the 3e era. RAW-uber-alles and 'entitlement' and whatnot. But those attitudes are mostly changing with 5e's shift in focus. I'd expect most 5e players to be a lot more accepting of any variant, whether it's adding options or restricting them. What're they gonna do? You can't remotely play the game without a DM, and not just anyone can DM.
Several players I gamed with during 3E/Pathfinder felt very strongly that anything "official", meaning published by WotC or Paizo, should be available in the game. It was really difficult to get them to see it any other way, and regardless of the outcome, we often had undue stress at the table.
I'm surprised you can get them to try 5e. If they don't run screaming from the new edition, it just might rub off on them, though.
Now, those players aren't still with my group, and 5E seems to have shifted things back to the DM making these kinds of judgement calls...so likely it wouldn't be an issue...but I'd just rather not find out. That's my purely selfish reason to be anti-splat.
(That'll show me for replying before I finish reading the whole post! I feel silly, now. ) Your problem players are gone, 5e is fostering trust of DMs, I think there's every reason to be hopeful that you won't have those kinds of issues, this time around!
Yeah, I think we've had several iterations of the ranger to the point where there isn't even a consensus on what the class should be.
I blame Strider. If Tolkien hadn't labeled him as a Ranger, I don't think the class would exist.
Or it'd be called something else Strider-referent, but not copyrighted by the Tolkien Estate...