"Jehovah's Witnesses do not celebrate pagan birthday's, but have no problem celebrating wedding anniversaries, baby showers and bridal showers. Why don't these displease God? The Bible never mentions these events!"
That's a lame rebut to this issue.
Anniversaries of one's birth are not an accomplishment.
Wedding anniversaries are an accomplishment of a choice and longevity.
Showers are to give presents.
As for displeasing God. Our very existence on this planet displeases God. But Jesus came and cleansed that. So God is not displeased by what we do.