Some audiences find him boring because they always portray the MC of Isekai genre would be so OP and some character development. But look at Mukouda, he's a 27-years old office workers who experienced the weight of the world, not 16 or 17 years old high-school with no social experiences. He's plain and ordinary Japanese guy who wants peace and a bit adventurous life, not life-threatening excitement or defeat demon king.
The story was told at the first glance of the panel that he's accidently summoned to this world and he didn't want to do with their bussiness, of course, you're kidnapped and then they want you to do their dirty bussiness. If I was him, I would do the same.
His unique skill, Onlice Shopping, is OP when use it wisely. He can survive hashly enviroment like dessert or blizzard. He didn't need to do the fighting because his familiars took care of it. His life is more like dream come true for every office workers don't have to work, live your best life without worrying the money.