Take a goblin, 10 base ac, 14 dex and leather armor. 13 ac in total. The most cookie cutter foe in Act 1 as far as ac goes. You're Joe Bloggs on the xbox. You've built your character right, a race with a bonus to strength. You have a 3 bonus and are using a weapon you are proficient in. This gives you 5 to hit against an ac of 13. This means you will miss the easiest foe well over 1/4 of the time, closer to 1/2. This does not sound like a good start to a mass market big seller. And this is the market Larian obviously hopes to hit, just look at all the percentages instead of numbers to roll. And this is with an optimised character, mind you.
Before they introduced the druid guiding light was the only way to induce advantage by spells and that's no easier to land than a weapon without some other way to help it. And they certainly didn't introduce the druid just so players could spam fairie fire so Laezal doesn't miss a goblin 7 times out of 20.
There's already threads complaining that the game is too hard, even with easy to obtain advantage. Can you imagine how many party wipes the three intellect devourers will cause at the start of act 1 without advantage?
No, the game is balanced already. Not completely tweaked, but balanced for those who don't know or don't want to learn the various ways to gain advantage. The question is, will they allow an option to switch off these systems for those who want a more core experience? I hope they do, because that's the sort of experience I'm looking for.
Advantage is pretty much baked into dnd, obtaining it via various spells or class abilities tends to be crucial to the game. I read a physicist who said his publisher once told him that every maths equation in a book was worth roughly 10% less sales. I have a feeling it's the same with manuals and videogames. I definitely don't think simplifying advantage is unbalancing, I just agree that that makes the game lose a lot of its flavour. It will however make the game easier for a lot of people and I have a feeling that is their primary motivation.
btw elevation clearly provides cover and allows you to see the whole body of your target in turn, offering an easier hit. An archer only exposes his head and the top of his body and bow, while below all is exposed. Obviously the higher the elevation the better the cover.