Um... How do you know what you've been ignored? By the fact they didn't immediately redesign their website following your email? :). Unfortunately it's a bit more complicated than that, especially since you say that it's a popular website (which usually implies that it's big, meaning that a redesign involves a huge amount of money, politics and work).
Horizontal menus don't scale very well in terms of top-level items, but they can incorporate up to two levels of submenus relatively easily. Vertical menus can easily be wider (more top-level items), but they don't scale well in terms of depth, and two levels might feel too much.
This depends on the specific site, but adding a navigation level is in itself a valid solution, and it doesn't automatically mean that it's not as good as adding a top-level menu item.
That is actually one of the problems with vertical menus. Since they scale so well, the owners are often tempted to keep on adding items, ruining the menu, instead of changing the structure and improving the IA by adding a level.