Although I couldn't find an explanation of this change, the most likely reason is to make better use of the Xfce project's limited number of developers by not allotting resources to a feature that is already well-developed elsewhere. At any rate, anyone who uses technologies such as FTP, Windows Shares, WebDav and SSH servers should benefit directly from the change, even though they may be unaware of the change.
At a time when GNOME and Ubuntu's Unity desktop are simplifying the panel, Xfce is keeping its standard panel and rewriting it. The result is still recognizable as the quirky feature of early releases, requiring you to select Move from a context menu before repositioning a launcher or plug in, but is otherwise more flexible.
For one thing the 4.8 panel has more customization options than its predecessor. While in the previous release, you could adjust a panel by size, position, and width and set it to autohide to give you more screen space, in the new release, the panel can also be locked and given a background consisting of a color or an image. You can also adjust a panel's size by either pixels or percentage of the total screen in 4.8.
In addition, the 4.8 panel introduces the concept of what might be called item spacing. That is, instead of being automatically added to the panel, as in old releases, an icon or plug-in must either be added to an existing space, or else a new space must be created for it.
This arrangement seems needlessly fussy at first, but it helps you to organize the panel more to your liking, and reduces the conflict between panel width and the number of items on the panel.
Moreover, each launcher space can become a sub-menu or drawer of its own, with its own items. These sub-menus are a practical alternative to too many icons on the desktop, or to the various efforts to eliminate the space occupied by the classical or accordion-type main menu when it is open. Either way, the sub-menus help to keep Xfce simple in its layout.
Xfce's 4.8 panel
Xfce 4.8 tweaks the desktop here and there, but mainly it should please existing users by being an updated version of what they already have.
However, the new release is also a timely one. For one thing, as the market for netbook and tablet computers continues to grow, Xfce's design philosophy may be exactly what users need.
Just as importantly, the second quarter of 2011 should see the release not only of Ubuntu's Unity desktop but also the release of GNOME 3.0. Both push the graphics capacity of free video drivers to the limit, and -- despite Unity's simplistic appearance -- neither is particularly fast or response if the pre-releases are any indication.
Moreover, while both Unity and GNOME 3.0 have their supporters, both also have large bodies of detractors (or, at least, very vocal ones). In both cases, the complaint is the same: the new desktops are being developed without paying much attention to what users want. For this reason, the releases of GNOME 3.0 and Unity seem likely to be accompanied by a number of dissatisfied users.
If that happens, Xfce might easily see a sudden increase in interest. Unlike GNOME 3.0 or Unity, Xfce does not try to change how users interact with the desktop. Instead, it focuses on the basics, providing a basic desktop and focusing on speed and efficiency.
Faced with a choice of two new desktop concepts, some users may turn to KDE. But others just might consider Xfce -- and, if they do, then the 4.8 release will be ready to give them a clear alternative.