I understand that it works better for you/you prefer that style.

Which implementation was better can always be debated, I agree that it's a matter of opinion.
In my humble opinion, personalized menus were confusing because choices on the menus kept disappearing too if you didn't use the program often enough. Even if the list was in the same location, you did have to essentially look twice - first check if the program existed in the trimmed down list and then hover/click the arrow to show the full list and then relocate the program. Not only is the location of the arrow changing depending on how big or small the trimmed list is but the location of programs also changed as the list is rebuilt to show itself in its entirety. Changing locations isn't good for motor memory. Plus, there was no end user control given over how many frequently used programs should be shown in the trimmed list.
With the separation of most used programs into a separate area, you actually save a few clicks if your program is in the MFU list. You click Start and then the program. The MFU list does not change
that much and that often, it's fairly static except for certain programs replacing others. Plus you can pin any program which you always want to the top area. If it's not there in the MFU list, there is the All Programs list which is static (think of "All Programs" as the arrow you used to click, but the location of the arrow is also static now). As an additional improvement, we also have an option in Classic Shell to
sort the MFU list alphabetically so it's easier to determine if a program exists in the top most used apps. It also supports keyboard accelerators.
With personalized menus, the user could never be certain what's going to be in the menu when the trimmed down list was shown. One of the rules in usability is to let the user know what to expect and that it should be in the same place to aid muscle memory. But if the menus are constantly in a state of flux, you are never sure what to expect. Not only did the shortened list in "personalized menu" not always show a fixed number of programs but they weren't even sorted by name!
These arguments aside, there are technical challenges too. Implementing "personalized menus" will require solving several problems - understanding how exactly the personalized menus worked, adding new graphical elements to all skins and applying the system of what programs you use most often on the whole All Programs list. This can affect performance of the menu. Plus, the Windows 7 style uses a treeview which can't dynamically change.
Btw, the last open source version is available here:
http://sourceforge.net/projects/classic ... elease%29/ (The file 'ClassicShellSrc_3_6_8.zip' contains the source). Since it is the Classic menu which you are after, it should have everything you need. If you are a developer, you could modify and compile it yourself or submit a patch for it which adds personalized menus.