Sorry for the provocative title, but now I have your attention 
Disclaimer: I like this game more than AOS. I think this is a good game, better than Warhammer was. But, I actually do believe the rules could take inspiration from AOS.
Problem:
This game is hard for beginners. You need to buy, assemble and paint a lot of miniatures that is problem number one. The second problem is that the rules are complicated. It simply takes too much effort to learn and too much time is spend looking up rules, rather than playing. It is even difficult for semi-regular players. Im the only one in my gaming group who still plays this game. The rest have switched to other more accessible games, and have to some extend brought me with them. Especially once we became dads we have less available time. Sometimes months go by without a game of T9A (we play something easier & faster like Warhammer Quest). When I finally get to play T9A it is against a stranger, since my friends have given up. And then, even I have to look up a lot of rules, and I have played T9A since the beginning, and Warhammer since the 90'ies. I actually hope I will be playing against someone who plays a lot more than me, so he will remember the rules. A problem is of course, that such a veteran is likely to win big time. I see more people leaving than entering the hobby. Some go to AOS. The third problem is that while the core rules are super balanced, gone are some of the randomness and fluffy fun from GW. The giant used to be hilarious. Now he trows balanced dice. The Hellblaster Vollygun used to super good and super unpredictable, and yes unbalanced.
Problem in a nutshell:
This game seems as if it has been designed by super competitive tournament players, who wanted a complicated & balanced game. This game is not as accessible & fun to new players as it could be, or even old timers like myself with family obligations. There are simply too many rules. Too many things to remember (or forget). Individually, all these rules are probably cool and makes sense. Taken together, there are simply too many of them.
Could some of these things be combined?:
- Two different weapon skills
- Two different special saves
- Lots of similar words: large, tall, gigantic, towering presence and massive bulk
- Hatred, Frenzy and battle focus
- Front rank does not give a rank bonus, but it does give a rank (super confusing for new players)
- Warmachine & construct
- Poison attacks, toxic attacks, lethal strike, divine attacks, flaming attacks, magical attacks
Conclusion:
Dont get me wrong. This is a good game. And the game designers have done a fantastic making it balanced, listening to feedback from the community and presenting the rules in a coherent and simple manner. I also realise that most of the problems of this game which I have just mentioned, have not been created by the game designers, but are inherited from GW, especially 8th ed. However, if this game is to survive on the long run, it needs to be able to bring in new players and keep the ones like me, who love the game, but cannot be as dedicated as we once were. A rules simplification could be a step in the right direction.

Disclaimer: I like this game more than AOS. I think this is a good game, better than Warhammer was. But, I actually do believe the rules could take inspiration from AOS.
Problem:
This game is hard for beginners. You need to buy, assemble and paint a lot of miniatures that is problem number one. The second problem is that the rules are complicated. It simply takes too much effort to learn and too much time is spend looking up rules, rather than playing. It is even difficult for semi-regular players. Im the only one in my gaming group who still plays this game. The rest have switched to other more accessible games, and have to some extend brought me with them. Especially once we became dads we have less available time. Sometimes months go by without a game of T9A (we play something easier & faster like Warhammer Quest). When I finally get to play T9A it is against a stranger, since my friends have given up. And then, even I have to look up a lot of rules, and I have played T9A since the beginning, and Warhammer since the 90'ies. I actually hope I will be playing against someone who plays a lot more than me, so he will remember the rules. A problem is of course, that such a veteran is likely to win big time. I see more people leaving than entering the hobby. Some go to AOS. The third problem is that while the core rules are super balanced, gone are some of the randomness and fluffy fun from GW. The giant used to be hilarious. Now he trows balanced dice. The Hellblaster Vollygun used to super good and super unpredictable, and yes unbalanced.
Problem in a nutshell:
This game seems as if it has been designed by super competitive tournament players, who wanted a complicated & balanced game. This game is not as accessible & fun to new players as it could be, or even old timers like myself with family obligations. There are simply too many rules. Too many things to remember (or forget). Individually, all these rules are probably cool and makes sense. Taken together, there are simply too many of them.
Could some of these things be combined?:
- Two different weapon skills
- Two different special saves
- Lots of similar words: large, tall, gigantic, towering presence and massive bulk
- Hatred, Frenzy and battle focus
- Front rank does not give a rank bonus, but it does give a rank (super confusing for new players)
- Warmachine & construct
- Poison attacks, toxic attacks, lethal strike, divine attacks, flaming attacks, magical attacks
Conclusion:
Dont get me wrong. This is a good game. And the game designers have done a fantastic making it balanced, listening to feedback from the community and presenting the rules in a coherent and simple manner. I also realise that most of the problems of this game which I have just mentioned, have not been created by the game designers, but are inherited from GW, especially 8th ed. However, if this game is to survive on the long run, it needs to be able to bring in new players and keep the ones like me, who love the game, but cannot be as dedicated as we once were. A rules simplification could be a step in the right direction.