I understand those with Age 2+2 skepticism and those who were hoping for WW1 era for Age4. But why I don’t agree with them, I want to share my opinion.
1. There is no doubt that Age2 is the most anticipated, and most played of the Age series. Medieval Era of Age2 is presumably the most chivalrous with well documented battles and many Expanding and lasting Empires. But still that must not be the only reason for Age2’s popularity.
2. The battle mechanics of Age2 is also simpler yet effective of all the age series in my opinion of course. The research and resource extraction mechanics are also very effective and engaging in Age2.
3. Building walls around cities makes sense in Age2 and preceding eras than Age3 and succeeding eras. Because walls became almost obsolete with the introduction of better artillery like bombard units.
4. Medieval Era is also longer than Industrial and modern era and that can give more flexibility in civilization selection and campaigns.
5. The failure of Age3 formula with more gunpowder units which did not cash out as much as the developers were hoping for might also be the reason for choosing medieval era. I know there are many successful entries with WW1 and more modern theme but it simply doesn’t fit in Age of Empires universe. In my opinion of-course.
So those who say, it is an Age2+2 not 4 and people will refuse to buy it when they already have an Age2 with much less price are totally wrong.
I think in next 15 - 20 years there will be another Age4+4 with the same medieval theme and people will love it.