Maybe you would've, but you've got a far, far better chance of attracting players to the club if you're playing Cap Prem/Cap 1 than Cap 5. The men's side of the club is almost completely dead, you're right, but killing off any competitive men's football isn't how I'd go about a rebuild. Its not like the clubrooms is the only thing that makes a club.
They have far, far more time to recruit to Cap Prem than they did to Central League, that's the obvious thing that's changed, but also they don't need to be at quite as high as standard, so a bigger pool of players to pick from.
The money is an interesting point and I'm not involved with Wellington United so can't comment on club finances other than to say they appear to have plenty for the women's game.
I think staying in Central League is what they refer to as a "no brainer" and any other decision would've been ridiculous.