I'm not. I'm asking an honest question. I don't know why you've decided to not answer. I am not asking what your issues are with the game. I think I've made that pretty clear at this point, that's not what I am asking. If you just don't want to answer for your own reasons, OK fair enough. But I don't get the responses you've given so far.
Alright, I'll bite then.
D&D 5E's beauty is in its simplicity and flavor, but these things can work against it.
The game has solved many complaints of past editions such as combat being very grindy at high levels.
This for me personally however comes at a trade off. The simplicity of the game I fear will limit by long term enjoyment of it, because system mastery is too easy to achieve.
It's too hard to build challenging encounters quickly. It's too easy as a player to gain system mastery. As a war gamer, this is concerning.
This also is a byproduct of bounded accuracy. Bounded accuracy on one hand has simplified the game mechanics, and also improved longevity of the game by making weaker creatures more relevant for longer, but it has also made the balance much harder to get in that sweet spot. 8th level parties can take down a CR16 Dragon for example. The most absurd example I have seen is the Dragon at the start of HoTDQ (CR16) being taken out by a Level 5 party. No matter how badly you played a monster in 3.5e, this would never happen.
The only real bit of content in the game that I have read and thought "wow, that's a challenge" is Taimat, everything else is sub par. Ultimately for me and my group, who are wargamers and not storytellers, this is a problem.
It creates more work for me, work I'd rather not be doing. I'd rather be using content to create encounters, adventures, etc rather than play testing Wizard's of the Coasts work to ensure it's an appropriate challenge, and spending a lot more time reviewing monster CR's and such to ensure they really are going to be an appropriate challenge.
Don't get me wrong, these complaints do not equate to "This game is not fun". It is fun. However, I would have liked them to spend more time focusing on the maths of monsters and how that relates to CR, and more time on how to build effective encounters for groups who like to min/max (where deadly really does mean deadly). Also I would have liked them to have spent more time building a system for actually creating challenges (monster or otherwise) instead of fluff and inspiration on how to do it. The monster building stuff at present is not really a system, it's more advice, and it doesn't live up to my expectations. What's worse is there is only a bare bones system for building challenges out of combat, and in my opinion, this is not good enough.
I would also have expected spells/feats to be more balanced since this game went through a lot of play testing. It took my group a couple of weeks to find some spells/feats/combinations that were just so good you will never pick any others. This limits tactical choice, and has a negative impact on the longevity of the game when you're just doing the same thing over and over.
Yes, the DM can house rule, but as wargamers, we like to play by the rules, and as those who enjoy system mastery; if the system is arbitrary then there is no enjoyment out of mastering it.