Hi,
so TI4, I think, made a step in the right direction. It threw out a lot of unnecessary overhead stuff, streamlined research, and generally understood that playability and game-flow comes before "lets push another of those insane ideas we got into the game, independent of implications".
The action deck got smaller, and reliability of stuff is higher. Politics card have less useless stuff, and agenda phase re-design is gorgeous. So overall, I am happy with TI4. However, there is one thing I still am not convinced about:
The way I think about it is this:
6 players gather to meet the whole day to spend a lot of time together. They reserve that day, and do a huge commitment. On top of this, since this is not a computer game, but a social experience, you also have that extra factor of "having a fun time together" in there. This approach, in my opinion, is totally contradicting any game design philosophy that works with elimination. I have done it, I have been on the receiving end, and ultimately, I have to say that this aspect of the game just does not fit for an hours game event where people come together to have fun. The person loosing it's home-system is frustrated, and has nothing to do, and the person doing it is maybe feeling remorse/regret. For more sensible personalities, being "a nice person" and not going for the kill, might actually cost them the game or otherwise make them play a less strong game.
In the end, I am convinced that such elimination game-play has nothing to do in a modern 2018 board game, and the euro-games design shows this. Games are fun till the end, and even the losers take part in it, till the game comes to a conclusion with all participants being part of the game round at the end.
Imho this approach would be much better for a TI game, given the investment players do to play one match.
My 2 cent.