Opinions on naming your son a "junior"

Okay so first pregnancy. My husband is 31 and in order for his family name to go on I would have to have a boy. (Of course we will be overjoyed whatever the baby is, we are 10 weeks 3 days, so won't find out for a bit) but my MIL insists if it is a boy that we should name it after my husband. I love his name, I think it's very cute but I just can't shake the feeling that I want to broaden our horizons when seeking a name for our baby. My husband likes the idea of a junior but equally likes the idea of choosing a different name. However, the MIL is very consistent saying stuff like "well he's old for a dad, so having a junior makes sense" since when is 31 "old" for becoming a dad??? Even if we don't name the baby a junior, the last name will still go on. Am I crazy for being a little annoyed with this situation? It's almost like she's not open to hearing cute names we are excited to talk about. Thank you in advance for your advice ladies!