I would say that if a couple is hosting their own shower, and the registry is listed in the invitation, gifts are a main focus of the party.
I wouldn't have too much of a problem with a 'meet the baby' party hosted by the parents that didn't include registry information, and who responded to questions with "Oh, just bring yourself". In the same vein, I don't have a problem with someone who organizes a birthday get-together or going out for drinks before a wedding. The key is that you don't call it a shower (which obligates the guests to bring gifts) and it's either relatively low key (for going out somewhere, it is in line with the normal style of the social group) or the organizer pays for everything.
But when someone organizes their own party at which gifts are obligatory, or organizes their own party that requires people to shell out a lot of money or take vacation time, then that's going too far.
For what it's worth, I didn't have a wedding shower, because when I got married, I was living in a culture that doesn't do showers, and was a long way away from most of my friends and all my family. If I have kids, I won't get a baby shower, for similar reasons.