The new site builder is probably intended to be less intimidating and more user friendly for first timers based on its cartoonish appearance.
However, the old version was more along the lines of more professional web creation tools as it was "Word" based.

Everyone knows how to use MS Word or other word processing software. You can't get simpler than that. 
Plus more advanced users were able to insert and edit HTML code.

It may not look as fun, but is much more familiar to the average user. Most GDI members aren't here for fun anyway.
This is a business oriented customer base.

The graphics look like they are geared towards kids, not business minded adults. Besides, most kids are more computer savvy than adults.
The graphic interface only slows things down. Personal "fun" websites come with most ISP packages anyway, and they all use a word processor based
site building tool with optional advanced features.

I would definitely appreciate the option to choose between SiteBuilder versions.

Last, but not least, I use a Mac. The vague help pages say to "right click" for editing, but Macs don't have a right button and the standard "control click"
substitute doesn't seem to work.