Actually a realistic depiction of what a doormat MC would miss out in life. You miss literally every priceless moment of your life because you are chasing other peoples wishes like a loyal dog.
That's a terrible take, I think, as it makes light of the sacrifices that people IRL make for their duties and responsibilities, like first-responders, active duty military, and diplomatic staff.
Sansui, who didn't know his wife was pregnant at the time, was sent on a high-importance diplomatic mission to a foreign kingdom which is a 6-month one-way trip away from home. You think he should have just quit his job at a whim? Putting aside all of the noble and social obligations, such as his wife is a vassal of House Sopeid and a noble of the Arcana Kingdom (who, you know, put her life on hold to serve), there's the fact that Rain is being treated as a noble member of House Sopeid, going as far as a little sister to the heiress of the House, with all of the advantages and benefits that come with that upbringing.
You're saying he should throw all of that away?
That he's a doormat because he executes his duties and responsibilities with dedication, in return for social backing, support, and recognition? That he should throw away the years of work he's put in to earn the trust of everyone around him, the trust that he can be depended on and counted on NOT to make selfish demands that no one can go against, because he can single-handedly kill an entire nation?
He's not a doormat just because he follows the lawful orders given to him by the people who feed, clothe, educate, socialize, and socially back his daughter, as well as paying his salary and will be giving him a noble title and position.
Or are you saying that Ukyou, the man in charge of the Domino Republic, is a better man than Sansui, because he does what he wants and doesn't "chase other peoples' wishes like a loyal dog", or how Suiboku was in his younger days?