I wouldn't call this a "trend" - I haven't seen an increase in this type of thing (in fact, I've seen a decrease in usage). It is insanely annoying, though. I suspect some unqualified upper-management person randomly decided that this seemed to make things "feel more secure" or some crazy notion, and pushed for it. It seems more likely at banks and things like that, who aren't exactly known for their user-friendly websites.