It's entirely possible that they'll never be added to the game as a playable option, so until they are it seems counterproductive to play as one. Especially since the attempts to portray one through current limitations end up looking rather strange and/or goofy. The Gold Saucer bunny ears, for instance, don't really do a great job at reflecting a proud and fierce defender of the forest.

It also makes me question how many people here actually want male viera because they're interested in their lore and what they bring to the table and not just because they desperately want to play as a guy with bunny ears.

As for why male viera aren't leaving their forest and haven't been seen outside of it so far, it would appear that they're more competent and driven when it comes to upholding their people's traditions. If they do leave their forest at a later date, then hopefully the reasoning is fleshed out and plausible.