Why men are against of shifts in gender roles?

Some (not all) men are against shifting gender roles because, historically and presently the nature of gender roles typically put males at a societal advantage. So the concept of having shifts in these gender roles, means that many males are often nervous that they will lose the stability in the systematic designation of societal standing due to gender, that was always designed to favour them. Although these fears are irrational, as most of the modern movements in relation to gender roles are in favour of freedom of the individual, and not intended to put any group or person at a disadvantage.