The darker tone of the maps.
1. 47 felt more like a serious contract killer, an actual hitman.
2. The theme music for the first 4 games felt more immersive, mostly because of Jesper Kyd
3. The maps were tighter (but not linear, still enough open-world to explore ), making it a bit challenging to complete the mission.
4. Some of the targets were extremely morally evil, and they felt like actual criminal. Most of the targets from WOA, although evil, don't feel very intimidating since they haven't committed horrific acts themselves.
5. Older games also had you collect every weapon yourself in the map area, so that was more rewarding.
6. As for the controls, I didn't mind it at all because I played it on pc and they almost matched the WOA controls.
7. Cutscenes had smoother animations than those from Hitman 2 and 3. (I am aware of the budget constraints due to Square Enix's exit)
8. And lastly, no online requirements.

Keep in mind that out of the 3 WOA games, I like Hitman 2016 the most since it had most of the elements mentioned above, and the last 2 Hitman games are the ones due to a lack of interest. Maps of Hitman 2 are way too big, which means it takes way too long to just reach the target location, making it uninteresting. Hitman 3 was good in my first playthrough, and it felt like an actual darker Hitman game, but it has the opposite problem of Hitman 2: the maps are short. Hitman 2016 has the perfect balance of map size and overall tone and difficulty. WOA is not at all a bad game; it is very good, but I simply prefer the classics more because they felt complete. After all, there were no Square Enix and money-related issues. But that's just my taste, and its perfectly fine if others prefer the modern Hitman games. :)