To improve installation, you could use an installer like http://nsis.sourceforge.net or http://www.jrsoftware.org/isinfo.php.
Now, VC++ DLL are included in Pencil2D. You could remove them and the installer could test if VC++ is installed and if not, download and install it, like HandBrake, HexChat, ShareX, PHPServer or Shareaza are doing. So, proprietary code would be separated from free code and we will have less files to download.
@numopen thanks for the suggestion. Hopefully one of the lead devs like @chchwy can take a look at that to see if it’s suitable for Pencil2D right now, but truth be told we’re missing a few developers these days, there’s simply not enough, a few of the “core team” said starting next month they would resume work, but other than that this project is halted until further notice. Thank you for your interest!