The concept of polish or lack thereof and the concept of well-developed and fleshed-out mechanics and robust technical side of the game are very different things. One does not exclude or apologize for the other.
Discussions about price ranges, RRP, and marketing strategy of publishers are for the most part very pointless, but from a technological and visual point this game is now, just like it was in the first closed beta build, a title that qualifies for 25-40$ range, at best.
And it has nothing to do with art style, how textures look, scale of models model, etc. This is a flagship game from arguably the best RTS series in history, and certainly one of the most important series on PC, and it is very underwhelming and in most aspects- barebones and dismaying, considering how few ‘big’ RTS game series exist, and how many years pass from one installment to the other.
Developers by no means are obliged to make their game groundbreaking, on any level, or obliged to not aim for the broadest possible player base out there. At the same time, players have all right to maintain high expectations and hold up huge titles like that to a certain standard
It’s a well-known fact that most purchases are from people focused on solo/coop modes. And these modes, especially on release, were poor. Campaigns are still unfulfilling- some missions are very simple and relatively short, most have borderline zero replay value, percentage of non-base building ones is much greater than in any other AoE game.
Overall I like them, like the video, style, presented history, narration, no annoying politicizing etc.
But these are games not documentaries, and gameplay is the most important aspect. Some missions are great, some feel like demo versions. Weirdly it reminds me of Hitman: Absolution 
Nothing can conquer with AoE2, especially 2DE, but even AoE III with much smaller campaign content at least offered very very decent solo and multiplayer skirmish options, where IV again- was kinda barebones even to late 19990s standards.
Glass is always half empty one way or the other- I’m 100% fine siding with the view ‘game was not rushed, development was smooth, developers just received less time than the game, or they, needed to deliver what was meant to be delivered’ They did a fantastic job within given timeframe.
Thing is- from the player’s perspective this was fifteen years.
There are some great-looking strategies on PC, but for the most part they are of economical type, builders, grand, 4X.
I, nor anyone I’ve seen on this forum before the release of IV, was asking for a potato-ready, clean, pro-play broadcast-friendly game, that could’ve been mistaken after the first screenshot reveals as a high-end mobile title, focused on PvP.