I am fully aware of everyone proving disrespect to Activision Blizzard since, like Ubisoft, they don't deserve any respect these days since they easily milk every single franchise they own until one dies out. Call of Duty used to be a good franchise, but now I can see its the worst offender, and everyone is likely to be burned out from it. This is the best example of using an established franchise for easy money. This series as a whole popularized many things which are now considered standard for first person shooters, such as aiming down the sights, player progression in the multiplayer and regenerating health.
Because the series has been going on for so long (it stared back in 2002 or 2003) it's very apparent that the developers are losing less and less interest in trying to make a meaningful game seeing how the campaigns have fluctuated in terms of quality. This started with Ghosts, but arguably this goes as far back as original 2009's Modern Warfare 2. In addition, BO4has no single-player campaign mode. The series' success contributed to the over-saturation of shooter games in modern gaming. The series is notable for being one of the few first person shooter series to still have traditional linear single-player campaigns rather than an open world or be focused entirely around multiplayer, only one game focused entirely around multiplayer (Black Ops 4) and it wasn't well received and ended up being a flop. The level design is still incredibly linear to the point there is no reason to replay the campaign since most of the games are scripted.
Many games in the series now tends to have the back cover barely any description, in fact they usually have bunch of screenshots and literally say (Campaign, Multiplayer, Zombies) like they first did with Black Ops II (though that game is still awesome, don't get me wrong). It shows how lazy they've got with the series to the point they don't even bother with the cover.
Even more lazier is because of the yearly release schedule, a lot of the games are the same with little innovation aside from new maps, story, and weapons. As an example, a cutscene in Ghosts is recycled from MW2 (2009). In fact there is constant recycling and reusing weapon models and animations, the most notable case is the Modern Warfare Trilogy, as well with cinematic scenes as the aforementioned Ghosts cutscene recycled from MW2 (2009). Treyarch doesn't escape from that too, despite they were using their own reloading animations, in BO2 they opted to recycle animations from Infinity Ward games to weapons that already had different animations (examples: FAL, MP5 and Uzi), the reloading sounds for each weapon category are almost the same. Thankfully, that is becoming less frequent from Ghosts (despite its copy-pasted cutscene). Despite using the same game engine slightly modified for each game, Sledgehammer Games uses their own in-home engine for its games (AW and WWII). Infinity Ward is going for the nearly same way starting with Modern Warfare (2019), but keeping some id Tech 3 code used.
Advanced Warfare, Infinite Warfare and Modern Warfare (2019) are decent entries that at least tried to innovate the series. But, since Advanced Warfare, the games have been hideously monetized to hell and back. These often feature some of the most exploitative and predatory practices in the industry right now, be it microtransactions and loot boxes. Among them is the disgusting monetization of Modern Warfare Remastered, and Black Ops 4's post launch loot boxes. Also, since Modern Warfare(2019), the Call of Duty studios no longer optimize their games in terms of size, with a game like Modern Warfare (2019) itself taking 200 GB to install.
There are things like intel that you can find, but you get nothing for collecting them, let alone all of them. While most of the collectibles are pointless, the original Modern Warfare (including it's remaster), the remaster of MW2, and Black Ops III are the exception since you can unlock cheats in the first two games and the latter are actual items instead of laptops that the game will give you descriptions about and uses them as decorations in your HQ.
Since Black Ops 4,the PC versions of the games are only available in Battle.net, so the users can't make reviews for the games no longer. Activision probably made this decision due the bad reviews of former games of the series, just like Infinite Warfare, as well as to keep all profit for themselves and avoid Steam.
Most of the games are heavily overpriced with Black Ops II still being $60 despite being released in 2012; and instead of giving the games a price drop, they remove the normal edition from digital stores and keep the special editions with $60 instead.
Despite being a yearly series, they rarely shut down the online servers, in fact the first game is still active despite being released over 20 years ago, and Call of Duty 4: Modern Warfare is very active on the PS3 and 360 despite them being legacy consoles and even despite many servers from older games are filled with hacked lobbies and cheaters.
So what is the future of this franchise? Will Activision Blizzard ever learn to deserve respect...or will they continue this franchise forever?