Maybe the better question is if The Infinity Watch SHOULD be a part of the MCU since when it comes to the comics, the group didn’t exactly cover themselves with glory given that following the original Infinity Gauntlet series. But with Adam Warlock coming to the MCU eventually, presumably to stick around for a little while, it kind of begs the question of whether or not we’re really done with the Infinity Stones, even after they’ve been seen as paperweights in the Loki series, which was pretty comical to be fair. The whole idea of the Infinity Watch was that they were to be the guardians of the stones after the evens of the Infinity Gauntlet series, with one person taking care of each stone. Warlock held onto the soul stone, Gamora was given the time stone, Drax was given the power stone, a character named Moondragon was given the mind stone, while Pip the Troll, who was recently introduced during the post-credits of The Eternals, was given the space stone, and Thanos of all people was given the reality stone. Yes, that’s really how the story went.
Unfortunately, they turned out to be the worst guardians for the stones since there was too much infighting, they didn’t agree on various actions that were taken by Warlock, and the group disbanded after a while due to their various differences. On top of that, they were targeted thanks to the desire that others had to take the stones, and as far as being a cohesive group, yeah, that didn’t really happen that often. The reason that there might be a problem with this in the MCU is that the current version of Gamora is from the past and has exhibited no knowledge of Adam Warlock, who has yet to be unleashed in the MCU, while Dave Bautista has already made it clear that his time as Drax is drawing to a close. It’s even been rumored that Moondragon isn’t going to be joining the MCU, but things do change so that might be up in the air at the moment. Thanos was turned to dust, however, so it’s fair to state that he won’t be around for another movie unless the MCU deems it necessary.
Pip the troll has never really appeared to be a responsible character at any time in the comics so it feels more like familiarity with the character that made Warlock trust him with a stone than anything, as Warlock hasn’t been the most stable character during his run in the comics anyway. There’s nothing saying that Warlock couldn’t go off and find the stones on his own in the MCU and initiate the next stage of the Infinity saga, which was the war against his dark side, the Magus, or the Infinity Crusade, which was a fight against his better side, the Goddess. It does feel as though the Infinity storyline has run its course for now though so it’s fair to think that such a thing wouldn’t come around until it was deemed time to reboot something or use the multiverse to see how the saga might have played out in a different manner. It’s uncertain what’s going to happen with Warlock at this time, but it does feel that he’ll end up being part of a bigger story that won’t involve the Infinity Stones, at least not at this time.
It’s still not fully understood why Warlock hasn’t been brought forward yet, especially since he was such a big part of the Infinity Gauntlet series back in the day. His presence has been teased often enough that he could have been revealed before the Infinity Saga came to a close, but then there is the thought that it might not have been long enough for people to really get used to him and perhaps even see Warlock as an actual wielder of the gauntlet at one point. As it’s been pointed out, the desire to create a story that was similar to the comics but not the same has been one of the desires of those at the MCU, which means that taking Warlock out of the equation was another decision that might not have been popular with some fans but was still seen as necessary.
The truth is that Adam Warlock has been seen around the Marvel universe before and after the Infinity Gauntlet series, but a lot of times he’s been kind of an unknown entity that a lot of people don’t feel is as big of a character. In a way he’s kind of like a lot of cosmic characters, he’s useful when there’s something for him to do, but otherwise, he’s easy to simply push to the side. It’s fair to think that Infinity Watch if it ever does come up, will be much different, but it might not be as big of a deal in the MCU if it’s ever mentioned.