If her motivations are reasonable, then yes. I could see quiting some habits and perhaps a hobby if she can convince me those are leading the relationship towards a bad end.
Though, knowing myself, I know I would feel inflexible at first and try to keep doing what I like, though, in the end the most important thing for anyone is family and a wife is part of it.
If we have children and she asked me to do so for the sake of them and not to endanger their economical well being, I would then accept but if she can also promise to show some sacrife as well and save money herself from other activies and whims she spends money on, like shopping unnecessary stuff or eating in fancy places more than she is supposed to.
I would even encourage her to put that cash in a long term saving account for our holidays or something like it. I would not marry someone who would be willing to ask me for sacrifices when she would not do the same.
Great point of view and it could also express her deep desire and appreciation for the relationship if she is brave enough to raise her voice. I think many relationships are not necessarily very balanced and a wife would feel like she better not say anything. As you said, in the first moment it may feel awkward, but that's the case for both. But in hindsight I think as a man the right course of action would be carefully consider what's actually happening and why she said what she said instead of instantly feeling the need to push her back and stick to the habit.
As for sacrifices have to come from both sides, well I guess it depends on what we are talking about. Gambling can be a dangerous thing and a wife might feel anxiety that even if it seems to be under control today, it could get out of control tomorrow. It's not like she asks a partner to stop playing soccer for fun or not go swimming anymore. These hobbies don't involve the potential for addictions and tough long-term consequences.
Right, playing football or swimming does not involve future risk as gambling could develop into. But you have also keep in mind that in the eyes of the husband, it is a hobby and a source of entertament, one as a gambler do not see the risk of it beyond the money one is putting at stake right at the moment.
If you asked someone to stop gambling, in the mind it may not be very different from asking someone else to stop riding bicycle on the weekends or swimming with their friends at the local pool, all of them would initially feel attacked and those petitions would be seen as an injustice.
If a spouse can understand that before aproaching their husband and put herself on his shoes, then that would be a wonderful woman, instead of one who just wishes to impose her rules on every member of her family.