Must I enable the root account to install Matlab?

I'm trying to install Matlab R20112a on Ubuntu.

My problem is: I get access to the installation gui running ./install from a terminal, but the installer fails when it tries to write on the folder /usr/local/MATLAB/R2012a (even though I created this folder before running the installation).

I assume the problem is I need root privileges, but "root" is disabled in ubuntu.

I can install the program in my home folder, but this is not a good solution because I want access to the program for all users.

As explained here, you do not need to enable root logins to run commands as root. That's what sudo and its graphical frontends (like gksu/gksudo and kdesudo) are for.

Since install runs a graphical installer, and you can run it (but not as root) like ./install, you can run it as root with:

gksu ./install

Try running gksudo ./install from the terminal. This will run the install as root.