At the risk of making a very out of date post at this point, here's a few ideas:
1) I know that the stereotype is the snooty "Roleplayer" looking down his nose at the hack-n-slasher and making passive-aggressive swipes at him all of the time, but in my experience, the animosity mostly goes the other direction. It's very hard to talk about roleplaying in a forum like this without a cadre of anti-roleplayers coming in and vandalizing the thread, no matter how carefully you try to tip-toe through the obvious minefield.
2) One of the many side-effects of having more fully-fleshed out characters that players spend a great deal more time in developing is more of an emotional attachment to them. This has more of an effect on the game than I think a lot of people give credit to. In fact, I think that as that paradigm has come more into prominence, the decreased lethality of the game is positively correlated to it.
3) I think one of the biggest impacts on how much "roleplaying" you want in your game is probably correlated as well to the vector by which you came into the hobby. In the oldest days, NOBODY played D&D unless you were already a wargamer, which had a profound effect on how you viewed the game and your character. In the also old days, but not quite as old, I believe almost everybody came into the hobby through fantasy fiction, which impacted how THEY thought the game and the characters should be treated. More recently, many people have been drawn in because they already liked computer or console fantasy games, which probably also impacts their view on what D&D should look like, how it should be played and how characters should be treated. I personally think that this idea that vector into the hobby, possibly correlated by era in which you came into the hobby and the cultural zeitgeist going on at the time is something that "D&D thinkers" haven't paid enough attention to, and there may well be very interesting things to discover along those lines.
4) For full disclosure, I came into the hobby in the very earliest 80s, only played wargames at all as a half-hearted spin-off of my D&D hobby (in a reversal of the direction of the generation before me) and have EXTREMELY strong preferences towards making the game resemble the kind of fantasy fiction that I was familiar with when I started gaming. So strong, in fact, that I have an almost visceral reaction to even the idea of dungeons because it's such a game-artifact rather than one that has any resemblance to the fiction that supposedly was the inspiration for the game. Finding the balance between enough character depth to be interesting, but enough risk and danger to be exciting is sometimes hard, but I think the secret is to not spend tons of time making character backgrounds and backstories, and whatnot. It's much easier to give characters rather broad personality traits or ticks, and start off with that; any additional depth is usually best developed in play rather than spelled out ahead of time. To do this, I think giving "dangling character threads" to the GM that he can pull on as appropriate is a good strategy too; things that aren't necessarily fleshed out and made too precious by over-attention, but just potential things that may or may not become important and/or interesting as the game goes on.
I also think using something like FATE's character links system when developing the "ensemble cast" that is the player character group helps too, because it gives instant hooks to roleplay on and banter back and forth between the characters for very little effort. That kind of stuff; practical roleplaying stuff that you can sink your teeth into without investing so much that you find your character too precious to risk in adventure, etc. is what I prefer to focus on.
5) UPDATE: Oh, another thing; I have also very strong preferences about player vs GM sovereignty, and I think that the GMs (or the system, for that matter) have no business intruding into player sovereignty (or vice versa) without a high risk of it triggering disappointment and/or conflict over how the game should be played. Respect of "sovereignty" is one of my key attributes as a GM that I think it crucial, but again, I don't hear people talk directly about it very often. Although I feel like people talk around it a lot without necessarily having the terms to talk about them very well.