I get what you are saying but I think I fall on the other side of the issue here. I really love the old school versions of D&D that didn't really have any skill systems at all beside a simple ability check (roll under relevant ability score - this is actually a surprisingly simple and effective mechanic that totally gets rid of fiddly modifiers and makes ability scores mean a lot). I DMed a lot of 3rd and 4th edition and good god once you got into higher level play everything just took FOREVER. 4th was worse than 3rd in that respect but really both of them just took forever to finish combats or do anything. I really like the return to a more streamlined gameplay. To me the advantage/disadvantage mechanic goes a long way to returning to a style of gameplay I really like, where creative thinking on the part of player or DM can really change a combat or non-combat situation. in 3rd or 4th edition it was more like, roll your way out of every situation. In 5th edition now if you can come up with some creative way to give yourself advantage, or to put your enemy at a disadvantage, that means more than complicated mechanics and multiple rolls.