In my opinion optional rules do not work.
Either they are so well supported that they are core or not supported at all and are nothing more than suggested house rules.
And considering that the complexity increases with each optional rule you support I think 5Es optional skill will be the latter.
Have to agree with Darren, for dthe game designer and for the adventure writer, having an optional skill system does make things trickier. You have to take bot skills and no skills options into account and balance around both.
Just reading this stuff I am for sure not going to play...
It seems every edition since 3e is going to be more and more simplified....
if i want simple. I will go play Dragon age or skyrim. Any videogame really.
For me it would be . . . .
Having enough people interested in buying/playing it longterm or at least giving it a go. If my gaming friends aren't interested, it's pointless for me to buy it.
For a start I won't even look at it until I have read a wide range of reviews, particularly from players whose opinion I respect i.e. not given from a biased perspective.
The only real deal breakers for me:
A clear and simple DM guide to create easy, medium and difficult challenges (but ultimately fair challenges) for PCs
Easy to run, but interesting, challenging and emblematic monsters with practical combat stat blocks.
All classes are as enjoyable to play as the others in their own way i.e. no glaringly bad classes, overpowered classes, boring classes.
PCs feel heroic not pathetic e.g. lv 1 characters not outmatched by house cats
Classes do not suck for 5 levels and then become gods, making everyone else feel pointless.
Class features available so that classes don't have to resort to using completely anti-iconic weapons in order to have something to do in combat e.g. a wizard using a crossbow.
High Level Spells do not break the game
Mechanical rules are slick, relatively simple, and easy enough to memorise so that having to refer to the rule books to adjudicate a decision does not happens on a regular basis.
And here is a real big one for me: The ability to have full on tactical combat where terrain and positioning are significant. I would be fine if this was a dial I could turn up or down as the significance of the battle varied, as long as a genuine, fully developed option still exists.
My deal breakers :
- the lack of native support for Low Fantasy : no christmas trees, no cheap magical effects such as at-will damage, plentiful healing, low-level shapechanging, casual divinations, easy resurection, effortless teleport, ...

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.