Finished Birthright and Conquest, so I thought I'd address some of the criticisms surrounding these games.
Birthright and Conquest are, in fact, different games. They have different stories, different consequences for your decision, but most importantly, they *play* very differently. Birthright in ways is easier than Awakening and an entry point into the series. Conquest is more difficult than both Birthright and Awakening, and demands a more varied and thoughtful approach to the battles. If you don't want to play Birthright, you don't have to; like I said the stories are different and you're not going to glean much insight into Conquest's story by playing Birthright. They re-use elements like settings, music, and some characters, but that's reflected in the price. The fact is you're getting two different, lengthy gameplay experiences if you pay for both games and that's the important part when it comes to charging you twice.
The six chapters of shared content end up being two hours when you convert them to game time. Both my save files were around 35+ hours, so you're looking at two hours of shared content against 70+ hours of distinct gameplay. You can start your second or third path right from this point, so it's not as though you're playing through it multiple times either.
I'm pretty sure this was the case in Awakening as well, but the support conversations are completely avoidable by pressing start at the beginning. If you don't enjoy the "dating sim" aspect of the game you don't have to see it and you'll still get the stat boosts and paralogues. There's little benefit to using most the other features, so you can avoid those as well. The only way this is an issue is if you're offended by it being in the game in any capacity. Otherwise, you can almost completely avoid the "dating" aspects and be no worse off for it in a gameplay sense.
Unfortunately, it seems as though there is some merit to the argument that you need Revelation to get the complete story. I've only just started (currently at Chapter 10), but even as early as the first couple of chapters there's a "revelation" that goes a long way in explaining one of the more interesting questions that remains mostly unanswered in the main games. A lot of motives are likely going to be explored in much greater detail in this path.
All in all, if you loved Awakening, you're probably going to love Fates. I'm over 100 hours in when you count restart time and Revelation is still the only thing I really want to play.