1 - Because they're American and therefore must be tacky, tasteless, yada, yada..
2 - Because the British don't understand what they are and most of the truly nice elements of the baby shower have been lost somewhere en route eastwards across the Atlantic.
Or maybe it's just something in British culture that is alien to the spirit of community and supportiveness that baby showers represent. What is the utter meanness about? The judgeyness and accusations of being 'grabby'? Why does something simple and nice have to be turned into such a complex and fraught incident involving guilt and resentment and obligation and cynicism?
I live in the US and have been to several baby showers, and several were thrown for me too when pg with DD1. They are lovely events.
My exMIL threw the first one, which was attended by my SILs and some of MIL's neighbours and her friends, a very sedate event. We had sandwiches and cake and non-alcoholic beer. The second was a surprise shower thrown by the people I worked with on a Friday afternoon shortly before I went on mat leave. The whole office attended; every one had hidden goodies they had bought or baked for the event, as well as a high chair and carseat... I never suspected a thing. It was very jolly. All of the gifts I got from both showers were used by DD1 and her four siblings in turn - A homemade crocheted blanket, little stuffed animals, the high chair, the car seat, a stroller, a little plate, sippy cup and baby cutlery set, a musical cot mobile featuring little bears which played 'Somewhere Over the Rainbow', some Beatrix Potter books, baby towels, cot sheet sets, a set of cloth diapers that I used as muslins, a baby monitor, and more.
One of exMIL's elderly neighbours threw a wedding shower for me too, when I first arrived in the US. The gift theme was kitchen equipment. Invitees included my SILs, their female cousins, some neighbours, and some friends of exMIL's. She booked a private dining room on one of the top floors of a hotel and we had a very ladylike luncheon featuring cold cucumber soup, iced tea, caesar salad, rolls, and assorted petits fours, with tea or coffee afterwards.
I still have many of the items that were given that day too.
So shoot me.
FWIW:
Baby showers are never thrown by the expectant mother herself. It's something a friend or aunt or grandmother would do and the intention is to honour the mother and provide practical support to her as she prepares for the baby's arrival. They have evolved of course, but the basic intention of honouring the mother (and motherhood itself) remains.
..............
'Gender' reveals otoh - YUK
And it's sex, not gender.