Have you ever played an RPG? Or Diablo?
Of course it's a buff, and you're stuck with it - that's why it's a MUCH BIGGER tradeoff than Civ IV civics. There's no going back.
And versatility? There are literally hundreds, perhaps thousands, of potential SP paths to go down, like any "talent tree" in an RPG. Not all of them are reasonable, probably, and not all are going to be optimal for the particular game you're playing. There are strategic decisions to be made in every game about how to approach the SPs, unlike civics, where you know what combination to use at every stage of every game. We might actually have to think about them each game, instead of using our standard civic combos in each phase. How is that LESS versatile?
Two things, first we are looking at this from two different angles I think. You're looking at versatility as it pertains to replayability we're I'm looking at it one game at a time. Yes, each game you can go down a different path and there are thouasnds of options but if you look at it one game at a time you are locked in as you go. Yes this can make the game more challenging because you can't change but that doesn't equate to more complex.
My second point is we both know that eventually the civ community is going to find out what the best paths are and everyone will be using them. Happens with almost every single game out there.
The simple fact is SP give you a benefit that's locked in and effects your long term strategy while civics can be changed, effect you short term and maybe long term strategy, effect you relations with the AI and add anarchy. You can't convince that SP's are more complex. Now which on is better, that's a different story and the jury is still out. Like I said in my first post, I'm not arguing for or against either game, it's not which one I like better it just the fundamental basic of what each one does.
You use an RPG as an example. I see choosing an SP like deciding whether to put a point in STR or DEX. Simple choice, does it have long term effects? Of course, but once you decide what character you are going to play it's pretty simple. Civics on the other hand, and you'll have to forgive me because I haven't played an RPG in a long time, are more like alignment(?) choices. Meaning, if I do this deed it will make me more evil or more good, which effects short and long term, how people react to you or what they charge for items etc. you can counteract some if it with an opposite deed down the road or keep going down the same path. Not the best example I know but I think it makes the point.
One is a fixed choice that effects one thing(granted there are more of them) and the other is an opened end choice that effects multiple things. The later in book is definitely more complex.