Fantastico is a product (for pay, not free) from another company. When they issue an update, cPanel (another company's product) picks it up for their distribution. Finally, Lunarpages eventually updates to the new cPanel. LP doesn't control what's in Fantastico, and it may be quite a while between a new Joomla version, say, and its showing up in LP's cPanel/Fantastico. LP does (as far as I know) control what's in LPCP and can update it rapidly.

Your criticism is not the least bit factual, as you start from the assumption that LP can update Fantastico any time it wants to. It can't.

Yes, it would make sense to have up-to-date offerings from the control panel. LPCP was developed in-house, so will be much cheaper for LP to offer. I wouldn't be surprised to see LP eventually drop cPanel altogether and move all accounts over to LPCP. Of course, LP will then be responsible for keeping updated on their installer (Fantastico replacement) in LPCP.

As most well written scripts have a mechanism to update within the script admin panels, the versions offered in the control panels should not be that big a deal. While, the use of the installers supplied in Cpanel and LPCP make the actual installation of the script quite easy, once the script is installed, you should then update to the latest version using the scripts admin panels. Depending on Fantastico or Softalicous for updating the packages is just not good security practice. No matter who is responsible there is going to be a delay between the new release and its availability in the third party installers.