See, the problem is
@Lanefan, unless you do some form of "in order" roll up, then you always start with "I have xxx in mind".
Only to a point; and I should also mention here that I'm coming from a background where classes are gated behind stat requirements* (which is something I very much endorse) and some of those requirements are pretty tough.
So sure, I might have a Ranger in mind (which here needs 14-14-13-13-x-x) but if the dice give me just one really good stat and the rest are bland and boring 9-to-12s then it's no Ranger for me today; I have to go to (or come up with) Plan B.
* - under the standard array (15-14-13-12-10-8, isn't it?) five classes in my game would be impossible to achieve: Ranger, Paladin, Illusionist, Bard and Monk. Paladin and Bard aren't even achievable under point-buy, unless there's an awful lot of points to spend.
Because, well, you know that any character that's rolled is going to have a pretty predictable set of stats (and, let's be honest here, if it's under point buy, the DM will almost universally let you roll it again).
Depends. My own cutoff, if it matters, is if the average of the 6 stats is less than 10
or you've nothing higher than a 12 then you have the option to reroll. That said, I've seen characters start with something like 15-12-11-10-9-6 and still do really well; at the same time I've also seen characters start with something like 18-18-17-17-15-14 and die at the first opportunity.
The notion that you roll first and then decide what to play hasn't really been part of the game for a very, very long time. Like, as in 2e at the latest, and actually, with the 1e Unearthed Arcana rolling system, you chose your class first.
A rolling system that I've never known of anyone using, other than maybe one person on ENWorld who might have mentioned it.
WotC didn't start this at all. This was part of the game since the release of the 1e AD&D Dungeon Master's Guide. 3d6 in order was never part of AD&D.
I'm not advocating for 3d6 in order and probably never would other than for one-offs or gonzo games. But 4d6k3 rearranged? All day long.
The notion that I'm going to have to play this randomly determined character for the next hundred hours or more is something I most certainly don't want to ever see back into the game.
Ah - you're assuming it'll survive for that hundred hours.
It absolutely baffles me why DM's have such an issue with a player building to a concept. It's their character. How is it in any way, shape or form bothering you how I choose what to play?
My take on such things is that a player can always choose the basics*, but anything non-basic can only be achieved by random roll; this is specifically to keep the non-basic as unusual.
* - for example, in my game even if you hit the cutoff bang-on (which would be something like 13-x-x-x-x-7 where the 4 x'es add to 40) you can choose any of the basic classes - F, T, MU, or C. But for a non-basic class you need to roll higher, in some cases only very little higher and in other cases quite a lot higher.