But I do like the "DM's Best Friend". Advantage is a lovely additional tool, but it's NOT a replacement for a simple +2/-2. Sometimes, things should just impair your ability a little not halve your chances of hitting. Sometimes a bonus or circumstance should enable you to do more than otherwise possible.
Still, YMMV. One thing I would strongly suggest, though - if you're using the +2/-2 mods as well as dis/advantage, you should probably only apply one of the two at a time. That is, if you have advantage, any +2 modifier no longer applies.
Advantage/Disadvantage was found to be wildly popular with playtest groups, IN EVERY SINGLE PLAYTEST PHASE. So you cannot even argue the stupid "self-selecting" argument, since every phase had high levels of acceptance of that rule, from the beginning, meaning you don't have the effect of people dropping out if they don't like something. Bottom line, advantage/disadvantage is in the game, and the primary mechanic for this.
Personally, I love it, and have no desire for all those fiddly -2/+2 bonuses. Those things alter the actual DC you can hit, unlike advantage/disadvantage. By fixing DCs, everyone knows throughout the game, no matter what level you are, what a challenge actually means. I think it's a bit step forward for the game.
I love Advantage/Disadvantage best as a situational modifier in place of all those fiddly bonuses. Any time things change based on a round-by-round or even attack-by-attack basis.Personally, I love it, and have no desire for all those fiddly -2/+2 bonuses. Those things alter the actual DC you can hit, unlike advantage/disadvantage. By fixing DCs, everyone knows throughout the game, no matter what level you are, what a challenge actually means. I think it's a bit step forward for the game.
I don't know who you're arguing with here – I think Advantage is a great mechanic and a huge selling point of D&D Next.
I just think there is room for smaller circumstantial modifiers in the game.
Well half cover grants a +2 bonus to AC and Dex saves. So the developers of the game evidently are open to the idea of one +2 situational modifier at least.

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