There will always be people complaining about the game because the player base is so huge and varied. We tend to group the complaints as coming from a coherent group but it's really not the case. In a way it's an issue PG have created for themselves by trying to make a game that's "for everyone".
I think the biggest "valid" criticism of the game in its current state is the lack of novelty in terms of gameplay compared to previous games. For players who like all kinds of cars, who like building and racing cars just for the sake of it, the game has plenty to offer, that's undeniable. But for more "casual" players (for lack of a better term), the gameplay basically hasn't changed much since the past couple of games. I can understand the game feeling somewhat stale once the novelty of the map wears off. Drift attack is a step in the right direction though, albeit a small one.
If the game wants to keep players engaged in the long term beyond the core of the player base, they need offer a bit more in terms of new gameplay. Not just a few new cars every month through the same old festival playlist, while hoping the player base does their job creating new experiences in Eventlab. The Crew Motorfest (despite its faults) shows that you can do more even with a racing game. Their much deeper brand collabs, better uses of themes for events, expansions of the maps are all things Horizon could implement in some way. Or the online summits for example, which require you to be competitive online to get the best rewards before they're available to all players, is clearly something Horizon would never do in its current state for fear of "gatekeeping" some players, but could be interesting.
IMO, the devs do need to decide whether catering to the core base is enough for them (therefore losing some players, but could focus on better racing and stuff for car nerds), or if they want (need? cough*Gamepass*cough) a larger playerbase, in which case the additions to the game need to be a bit more significant in terms of gameplay.
Let's see what they give us for the 7 Eleven update. If it's just a reskinned konbini with a car meet, a livery you can only get in IRL stores, and PR stunts with some voiceovers, I'm sure I won't be the only one disappointed. But maybe the real novelty will have to wait until the DLCs. We probably all have high hopes & expectations for them.