Merlier is the best sprinter in the world. There are 5 sprinter stages, potentially 6, so of course you include him when you 'only' have the third favorite. And what are you bringing instead? Most pack fodder who will get dropped anyway and not be super useful when you don't have Landa anyway.
Meeus was plan B because Roglic has a tendency of crashing, especially in this race. They don't want a scenario where Roglic is out and then all you have is domestiques who barely can chase stages for themselves. Had he not had a habit of crashing, he would not even be here in the first place because he's not as good as Merlier. So thats sensible as well, although more debateable since you also have Lipo this year and Meeus is relatively far off Merlier's level. But he could easily have fluked another TdF win, and he has looked good recently.
Remember, its not like UAE is 100% for Pog and Visma 100% for Jonas. If that was the case, why did Adam ride for a podium in 2023 and why did Almeida also ride for himself in certain stages last year where it was mostly Adam doing the setups? In UAE's case, because comitting 100% to Pog in 2023 wouldn't have mattered, so getting another podium is quite valuable, and in 2024, because Almeida could focus a bit more on himself since Pog was so dominating. You could say you want riders staying relevant in GC, but Yates and Almeida were never threats of being used tactically at all. Thats not how it works when Vingegaard and Pog are 2 levels above the rest. One pedal stroke and they are caught. And what happens in case of your leader crashing?
Visma is a bit different, you have WVA who you need to give personal freedom in exchange of him staying on your team, but also comitting 100% on most other stages. The satellite job he did in 2022 was absolutely insane and impacted the race heavily. For example, I think Visma and Jonas should have taken it a step further and on Granon and Jonas should have dropped himself on Galibier, knowing that he had WVA to bait Pog into going 100% in the valley OR made an all-in attack there to really use him. No matter what, Pog had him in mind though, and thats why he was so scared in the first place to let them go from afar. Cobbled stage he probably saved Jonas at least a minute. Dropped Pog on Hautacam. WVA was an absolutely huge player in Jonas winning in 2022 and if my analysis is right that Pog lets Roglic go if Wout isn't there on Granon, I think Pog wins. Same thing happened on Cauterets in 2023 where Jonas again couldn't deal the final blow, because if he could drop him on Tourmalet, the Tour is over.. turned out to be over anyways, but even if you get dropped, you just get a free ride back from WVA. Thats just huge.
Every team has multiple riders with personal ambitions and there's absolutely nothing wrong about it IMO.