Effective April 1, 2013 the Joomla Extensions Directory will drop the requirement for index.html files in all folders.

Why the change?

The rule is obsolete and has not been an effective ‘security' measure for a long time. You can read more about it here: http://www.dionysopoulos.me/blog/86-the-files-of-wrath.html

The #1 error with extensions submitted to be listed in the JED is SE1 (missing index.html files) which significantly slows down the approval process for everyone.  Once the error is flagged, the developer has to fix it and then we have to re-screen it. The whole process gets unnecessarily long.

Once we approve an extension for listing it’s generally not checked again, unless there’s an issue reported. It’s quite common for a developer to update his/her extension and miss a few index.html files which will go unnoticed anyway.

What is the alternative?

Check with your hosting providers to see if they have directory traversal disabled.

Utilize the .htaccess / web.config file to prevent directory traversal.   

https://docs.joomla.org/How_do_you_convert_an_htaccess.txt_file_into_a_.htaccess_file%3F

https://docs.joomla.org/Htaccess_examples_%28security%29

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